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feat: add solutions to lc problem: No.2257 (doocs#3798)
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Diff for: ‎solution/2200-2299/2257.Count Unguarded Cells in the Grid/README.md

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Original file line numberDiff line numberDiff line change
@@ -246,6 +246,117 @@ function countUnguarded(m: number, n: number, guards: number[][], walls: number[
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}
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```
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#### JavaScript
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```js
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function countUnguarded(m, n, guards, walls) {
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const g = Array.from({ length: m }, () => Array.from({ length: n }, () => 0));
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for (const [i, j] of guards) {
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g[i][j] = 2;
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}
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for (const [i, j] of walls) {
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g[i][j] = 2;
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}
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const dirs = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; ++k) {
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let [x, y] = [i, j];
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let [a, b] = [dirs[k], dirs[k + 1]];
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while (x + a >= 0 && x + a < m && y + b >= 0 && y + b < n && g[x + a][y + b] < 2) {
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x += a;
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y += b;
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g[x][y] = 1;
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}
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}
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}
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let ans = 0;
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for (const row of g) {
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for (const v of row) {
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ans += v === 0 ? 1 : 0;
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}
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}
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return ans;
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}
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- solution:start -->
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### 方法二：DFS + 模拟
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<!-- tabs:start -->
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#### TypeScript
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```ts
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function countUnguarded(m: number, n: number, guards: number[][], walls: number[][]): number {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i: number, j: number, dx: number, dy: number) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}
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```
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#### JavaScript
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```js
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function countUnguarded(m, n, guards, walls) {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i, j, dx, dy) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}
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```
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<!-- tabs:end -->
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<!-- solution:end -->

Diff for: ‎solution/2200-2299/2257.Count Unguarded Cells in the Grid/README_EN.md

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Original file line numberDiff line numberDiff line change
@@ -242,6 +242,117 @@ function countUnguarded(m: number, n: number, guards: number[][], walls: number[
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}
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```
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#### JavaScript
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```js
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function countUnguarded(m, n, guards, walls) {
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const g = Array.from({ length: m }, () => Array.from({ length: n }, () => 0));
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for (const [i, j] of guards) {
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g[i][j] = 2;
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}
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for (const [i, j] of walls) {
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g[i][j] = 2;
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}
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const dirs = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; ++k) {
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let [x, y] = [i, j];
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let [a, b] = [dirs[k], dirs[k + 1]];
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while (x + a >= 0 && x + a < m && y + b >= 0 && y + b < n && g[x + a][y + b] < 2) {
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x += a;
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y += b;
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g[x][y] = 1;
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}
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}
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}
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let ans = 0;
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for (const row of g) {
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for (const v of row) {
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ans += v === 0 ? 1 : 0;
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}
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}
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return ans;
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}
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- solution:start -->
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### Solution 2: DFS + Simulation
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<!-- tabs:start -->
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#### TypeScript
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```ts
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function countUnguarded(m: number, n: number, guards: number[][], walls: number[][]): number {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i: number, j: number, dx: number, dy: number) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}
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```
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#### JavaScript
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```js
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function countUnguarded(m, n, guards, walls) {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i, j, dx, dy) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}
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```
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<!-- tabs:end -->
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<!-- solution:end -->

Diff for: ‎solution/2200-2299/2257.Count Unguarded Cells in the Grid/Solution.js

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@@ -0,0 +1,28 @@
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function countUnguarded(m, n, guards, walls) {
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const g = Array.from({ length: m }, () => Array.from({ length: n }, () => 0));
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for (const [i, j] of guards) {
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g[i][j] = 2;
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}
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for (const [i, j] of walls) {
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g[i][j] = 2;
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}
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const dirs = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; ++k) {
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let [x, y] = [i, j];
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let [a, b] = [dirs[k], dirs[k + 1]];
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while (x + a >= 0 && x + a < m && y + b >= 0 && y + b < n && g[x + a][y + b] < 2) {
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x += a;
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y += b;
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g[x][y] = 1;
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}
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}
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}
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let ans = 0;
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for (const row of g) {
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for (const v of row) {
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ans += v === 0 ? 1 : 0;
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}
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}
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return ans;
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}

Diff for: ‎solution/2200-2299/2257.Count Unguarded Cells in the Grid/Solution2.js

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function countUnguarded(m, n, guards, walls) {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i, j, dx, dy) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}

Diff for: ‎solution/2200-2299/2257.Count Unguarded Cells in the Grid/Solution2.ts

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function countUnguarded(m: number, n: number, guards: number[][], walls: number[][]): number {
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let c = 0;
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const mtx = Array.from({ length: m }, () => Array(n).fill(0));
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for (const [i, j] of guards) mtx[i][j] = 2;
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for (const [i, j] of walls) mtx[i][j] = 2;
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const dfs = (i: number, j: number, dx: number, dy: number) => {
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[i, j] = [i + dx, j + dy];
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if (i < 0 || m <= i || j < 0 || n <= j || mtx[i][j] === 2) return;
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if (mtx[i][j] === 0) {
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mtx[i][j] = 1;
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c++;
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}
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dfs(i, j, dx, dy);
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};
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const DIRS = [-1, 0, 1, 0, -1];
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for (const [i, j] of guards) {
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for (let k = 0; k < 4; k++) {
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const [dx, dy] = [DIRS[k], DIRS[k + 1]];
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dfs(i, j, dx, dy);
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}
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}
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return m * n - guards.length - walls.length - c;
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}

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