refactor: update typescript solution to lc problem: No.200

Author: rain84

solution/0200-0299/0200.Number of Islands/README.md

@@ -208,17 +208,17 @@ function numIslands(grid: string[][]): number {
     const m = grid.length;
     const n = grid[0].length;
     let ans = 0;
-    function dfs(i, j) {
+
+    const dfs = (i: number, j: number) => {
+        if (grid[i]?.[j] !== '1') return;
+
         grid[i][j] = '0';
-        const dirs = [-1, 0, 1, 0, -1];
-        for (let k = 0; k < 4; ++k) {
-            const x = i + dirs[k];
-            const y = j + dirs[k + 1];
-            if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1') {
-                dfs(x, y);
-            }
-        }
-    }
+        dfs(i + 1, j);
+        dfs(i - 1, j);
+        dfs(i, j + 1);
+        dfs(i, j - 1);
+    };
+
     for (let i = 0; i < m; ++i) {
         for (let j = 0; j < n; ++j) {
             if (grid[i][j] == '1') {
@@ -227,6 +227,7 @@ function numIslands(grid: string[][]): number {
             }
         }
     }
+
     return ans;
 }
 ```

solution/0200-0299/0200.Number of Islands/README_EN.md

@@ -198,17 +198,17 @@ function numIslands(grid: string[][]): number {
     const m = grid.length;
     const n = grid[0].length;
     let ans = 0;
-    function dfs(i, j) {
+
+    const dfs = (i: number, j: number) => {
+        if (grid[i]?.[j] !== '1') return;
+
         grid[i][j] = '0';
-        const dirs = [-1, 0, 1, 0, -1];
-        for (let k = 0; k < 4; ++k) {
-            const x = i + dirs[k];
-            const y = j + dirs[k + 1];
-            if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1') {
-                dfs(x, y);
-            }
-        }
-    }
+        dfs(i + 1, j);
+        dfs(i - 1, j);
+        dfs(i, j + 1);
+        dfs(i, j - 1);
+    };
+
     for (let i = 0; i < m; ++i) {
         for (let j = 0; j < n; ++j) {
             if (grid[i][j] == '1') {
@@ -217,6 +217,7 @@ function numIslands(grid: string[][]): number {
             }
         }
     }
+
     return ans;
 }
 ```

solution/0200-0299/0200.Number of Islands/Solution.ts

@@ -2,17 +2,17 @@ function numIslands(grid: string[][]): number {
     const m = grid.length;
     const n = grid[0].length;
     let ans = 0;
-    function dfs(i, j) {
+
+    const dfs = (i: number, j: number) => {
+        if (grid[i]?.[j] !== '1') return;
+
         grid[i][j] = '0';
-        const dirs = [-1, 0, 1, 0, -1];
-        for (let k = 0; k < 4; ++k) {
-            const x = i + dirs[k];
-            const y = j + dirs[k + 1];
-            if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1') {
-                dfs(x, y);
-            }
-        }
-    }
+        dfs(i + 1, j);
+        dfs(i - 1, j);
+        dfs(i, j + 1);
+        dfs(i, j - 1);
+    };
+
     for (let i = 0; i < m; ++i) {
         for (let j = 0; j < n; ++j) {
             if (grid[i][j] == '1') {
@@ -21,5 +21,6 @@ function numIslands(grid: string[][]): number {
             }
         }
     }
+
     return ans;
 }