0827:最大人工岛----添加js解法

Author: hp1998318

problems/0827.最大人工岛.md

@@ -348,6 +348,71 @@ class Solution:
 
 ```
 
+### JavaScript
+
+```JavaScript
+
+var largestIsland = function(grid) {
+let res = 0;
+const m = grid.length;
+const n = grid[0].length;
+const tag = new Array(n).fill().map(_ => new Array(m).fill(0));
+const area = new Map();
+const dir = [[0,1],[0,-1],[1,0],[-1,0]];
+const dfs = (grid,tag,x,y,mark) => {
+    let res = 1;
+    tag[x][y] = mark;
+    for(let i = 0; i < dir.length; i++) {
+        let nextX = x + dir[i][0];
+        let nextY = y + dir[i][1];
+        if(nextX < 0 || nextX >= m || nextY < 0 || nextY >= n) {
+            continue;
+        }
+        if(grid[nextX][nextY] === 1 && tag[nextX][nextY] === 0) {
+            res += dfs(grid,tag,nextX,nextY,mark);
+        }
+    }
+    return res;
+}
+let mark = 2;
+//将岛屿用mark标记
+for(let i = 0; i < m; i++) {      
+    for(let j = 0; j < n; j++) {
+        if(grid[i][j] === 1 && tag[i][j] === 0) {
+            area.set(mark,dfs(grid,tag,i,j,mark));
+            res = Math.max(res,area.get(mark));
+            mark++;
+        }
+    }
+}
+//将一个非岛屿格子变为岛屿
+for(let i = 0; i < m; i++) {
+    for(let j = 0; j < n; j++) {
+        if(grid[i][j] === 0) {
+            let z = 1;
+            const connected = new Set();
+            for(let k = 0; k < dir.length; k++) {
+                let nextX = i + dir[k][0];
+                let nextY = j + dir[k][1];
+                if(nextX < 0 || nextX >= m || nextY < 0 || nextY >= n || tag[nextX][nextY] === 0 || connected.has(tag[nextX][nextY])) {
+                    continue;
+                }
+                z += area.get(tag[nextX][nextY]);
+                connected.add(tag[nextX][nextY]);
+            }
+            res = Math.max(res,z);
+        }
+    }
+}
+return res;
+}; 
+
+
+```
+
+
+
+
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