Create 1254-number-of-closed-islands.js

Author: everthis

1254-number-of-closed-islands.js

@@ -0,0 +1,62 @@
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+const closedIsland = function(grid) {
+  const m = grid.length, n = grid[0].length
+  const arr = []
+  for(let i = 0; i < m; i++) {
+    for(let j = 0; j < n; j++) {
+      if(grid[i][j] === 0) arr.push([i, j])
+    }
+  }
+  const dirs = [[0,1], [0,-1], [1,0], [-1,0]]
+  let num = 2
+  for(const [i, j] of arr) {
+    if(grid[i][j] !== 0) continue
+    else {
+      bfs(i, j, num)
+      num++
+    }
+  }
+  
+  let res = 0
+  const set = new Set()
+  for(let i = 2; i < num; i++) {
+    set.add(i)
+  }
+  
+  for(let i = 0; i < m; i++) {
+    for(let j = 0; j < n; j++) {
+      if(grid[i][j] > 1 && invalid(i, j)) {
+        set.delete(grid[i][j])
+      }    
+    }
+  }
+  return set.size
+  
+  function invalid(i,j) {
+    if(i === 0 || i === m - 1 || j === 0 || j === n - 1) return true
+    return false
+  }
+  function bfs(i, j, v) {
+    let q = [[i,j]]
+    grid[i][j] = v
+    while(q.length) {
+      const tmp = []
+      const size = q.length
+      
+      for(const [x, y] of q) {
+        for(const [dx, dy] of dirs) {
+          const nx = x + dx, ny = y + dy
+          if(nx >= 0 && nx < m && ny >= 0 && ny < n && grid[nx][ny] === 0) {
+            grid[nx][ny] = v
+            tmp.push([nx, ny])
+          }
+        }
+      }
+      
+      q = tmp
+    }
+  }
+};