feat: add solutions to lc problem: No.1730

No.1730.Shortest Path to Get Food

Author: yanglbme

solution/1700-1799/1730.Shortest Path to Get Food/README.md

@@ -59,7 +59,15 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
-BFS。
+**方法一：BFS**
+
+根据题意，我们需要从 `*` 出发，找到最近的 `#`，返回最短路径长度。
+
+首先，我们遍历整个二维数组，找到 `*` 的位置，将其作为 BFS 的起点，放入队列中。
+
+然后，我们开始 BFS，遍历队列中的元素，每次遍历到一个元素，我们将其上下左右四个方向的元素加入队列中，直到遇到 `#`，返回当前层数。
+
+时间复杂度 $O(m \times n)$，空间复杂度 $O(1)$。其中 $m$ 和 $n$ 分别为二维数组的行数和列数。
 
 <!-- tabs:start -->
 
@@ -70,20 +78,17 @@ BFS。
 ```python
 class Solution:
     def getFood(self, grid: List[List[str]]) -> int:
-        def pos():
-            for i in range(m):
-                for j in range(n):
-                    if grid[i][j] == '*':
-                        return i, j
-
         m, n = len(grid), len(grid[0])
-        q = deque([pos()])
+        i, j = next((i, j) for i in range(m)
+                    for j in range(n) if grid[i][j] == '*')
+        q = deque([(i, j)])
+        dirs = (-1, 0, 1, 0, -1)
         ans = 0
         while q:
             ans += 1
             for _ in range(len(q)):
                 i, j = q.popleft()
-                for a, b in [[0, -1], [0, 1], [1, 0], [-1, 0]]:
+                for a, b in pairwise(dirs):
                     x, y = i + a, j + b
                     if 0 <= x < m and 0 <= y < n:
                         if grid[x][y] == '#':
@@ -100,20 +105,28 @@ class Solution:
 
 ```java
 class Solution {
+    private int[] dirs = {-1, 0, 1, 0, -1};
+
     public int getFood(char[][] grid) {
-        int m = grid.length;
-        int n = grid[0].length;
-        Deque<int[]> q = new LinkedList<>();
-        q.offer(pos(grid));
+        int m = grid.length, n = grid[0].length;
+        Deque<int[]> q = new ArrayDeque<>();
+        for (int i = 0, x = 1; i < m && x == 1; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == '*') {
+                    q.offer(new int[] {i, j});
+                    x = 0;
+                    break;
+                }
+            }
+        }
         int ans = 0;
-        int[] dirs = {-1, 0, 1, 0, -1};
         while (!q.isEmpty()) {
             ++ans;
-            for (int i = q.size(); i > 0; --i) {
-                int[] p = q.poll();
-                for (int j = 0; j < 4; ++j) {
-                    int x = p[0] + dirs[j];
-                    int y = p[1] + dirs[j + 1];
+            for (int t = q.size(); t > 0; --t) {
+                var p = q.poll();
+                for (int k = 0; k < 4; ++k) {
+                    int x = p[0] + dirs[k];
+                    int y = p[1] + dirs[k + 1];
                     if (x >= 0 && x < m && y >= 0 && y < n) {
                         if (grid[x][y] == '#') {
                             return ans;
@@ -128,95 +141,82 @@ class Solution {
         }
         return -1;
     }
-
-    private int[] pos(char[][] grid) {
-        for (int i = 0; i < grid.length; ++i) {
-            for (int j = 0; j < grid[0].length; ++j) {
-                if (grid[i][j] == '*') {
-                    return new int[] {i, j};
-                }
-            }
-        }
-        return new int[] {-1, -1};
-    }
 }
 ```
 
 ### **C++**
 
 ```cpp
-typedef pair<int, int> pii;
-
 class Solution {
 public:
+    const static inline vector<int> dirs = {-1, 0, 1, 0, -1};
+
     int getFood(vector<vector<char>>& grid) {
         int m = grid.size(), n = grid[0].size();
-        queue<pii> q {{pos(grid)}};
+        queue<pair<int, int>> q;
+        for (int i = 0, x = 1; i < m && x == 1; ++i) {
+            for (int j = 0; j < n; ++j) {
+                if (grid[i][j] == '*') {
+                    q.emplace(i, j);
+                    x = 0;
+                    break;
+                }
+            }
+        }
         int ans = 0;
-        vector<int> dirs = {-1, 0, 1, 0, -1};
         while (!q.empty()) {
             ++ans;
-            for (int i = q.size(); i > 0; --i) {
-                pii p = q.front();
+            for (int t = q.size(); t; --t) {
+                auto [i, j] = q.front();
                 q.pop();
-                for (int j = 0; j < 4; ++j) {
-                    int x = p.first + dirs[j];
-                    int y = p.second + dirs[j + 1];
+                for (int k = 0; k < 4; ++k) {
+                    int x = i + dirs[k], y = j + dirs[k + 1];
                     if (x >= 0 && x < m && y >= 0 && y < n) {
                         if (grid[x][y] == '#') return ans;
                         if (grid[x][y] == 'O') {
                             grid[x][y] = 'X';
-                            q.push({x, y});
+                            q.emplace(x, y);
                         }
                     }
                 }
             }
         }
         return -1;
     }
-
-    pii pos(vector<vector<char>>& grid) {
-        for (int i = 0; i < grid.size(); ++i)
-            for (int j = 0; j < grid[0].size(); ++j)
-                if (grid[i][j] == '*')
-                    return {i, j};
-        return {};
-    }
 };
 ```
 
 ### **Go**
 
 ```go
-func getFood(grid [][]byte) int {
+func getFood(grid [][]byte) (ans int) {
 	m, n := len(grid), len(grid[0])
-	pos := func() []int {
-		for i := 0; i < m; i++ {
-			for j := 0; j < n; j++ {
-				if grid[i][j] == '*' {
-					return []int{i, j}
-				}
+	dirs := []int{-1, 0, 1, 0, -1}
+	type pair struct{ i, j int }
+	q := []pair{}
+	for i, x := 0, 1; i < m && x == 1; i++ {
+		for j := 0; j < n; j++ {
+			if grid[i][j] == '*' {
+				q = append(q, pair{i, j})
+				x = 0
+				break
 			}
 		}
-		return []int{}
 	}
-	q := [][]int{pos()}
-	dirs := []int{-1, 0, 1, 0, -1}
-	ans := 0
 	for len(q) > 0 {
 		ans++
-		for i := len(q); i > 0; i-- {
+		for t := len(q); t > 0; t-- {
 			p := q[0]
 			q = q[1:]
-			for j := 0; j < 4; j++ {
-				x, y := p[0]+dirs[j], p[1]+dirs[j+1]
+			for k := 0; k < 4; k++ {
+				x, y := p.i+dirs[k], p.j+dirs[k+1]
 				if x >= 0 && x < m && y >= 0 && y < n {
 					if grid[x][y] == '#' {
 						return ans
 					}
 					if grid[x][y] == 'O' {
 						grid[x][y] = 'X'
-						q = append(q, []int{x, y})
+						q = append(q, pair{x, y})
 					}
 				}
 			}
@@ -226,6 +226,51 @@ func getFood(grid [][]byte) int {
 }
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+var getFood = function (grid) {
+    const m = grid.length;
+    const n = grid[0].length;
+    const dirs = [-1, 0, 1, 0, -1];
+    const q = [];
+    for (let i = 0, x = 1; i < m && x == 1; ++i) {
+        for (let j = 0; j < n; ++j) {
+            if (grid[i][j] == '*') {
+                q.push([i, j]);
+                x = 0;
+                break;
+            }
+        }
+    }
+    let ans = 0;
+    while (q.length) {
+        ++ans;
+        for (let t = q.length; t > 0; --t) {
+            const [i, j] = q.shift();
+            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) {
+                    if (grid[x][y] == '#') {
+                        return ans;
+                    }
+                    if (grid[x][y] == 'O') {
+                        grid[x][y] = 'X';
+                        q.push([x, y]);
+                    }
+                }
+            }
+        }
+    }
+    return -1;
+};
+```
+
 ### **...**
 
 ```