add: 只出现一次的数字等

src/array/number-of-islands.js

@@ -0,0 +1,32 @@
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+export const numIslands = function (grid) {
+  if (!grid[0]) return 0
+  const maxN = grid.length - 1
+  const maxI = grid[0].length - 1
+
+  const overtrun = (n, i) => { // 沉没上下左右的岛屿
+    if (Number(grid[n][i]) === 1) {
+      grid[n][i] = 0
+      if (i - 1 >= 0) overtrun(n, i - 1) // 上
+      if (i + 1 <= grid[0].length - 1) overtrun(n, i + 1) // 下
+      if (n - 1 >= 0) overtrun(n - 1, i) // 左
+      if (n + 1 <= grid.length - 1) overtrun(n + 1, i) // 右
+    }
+  }
+
+  let res = 0
+  // 1. 遍历所有的点
+  for (let n = 0; n <= maxN; n++) {
+    for (let i = 0; i <= maxI; i++) {
+      if (Number(grid[n][i]) === 1) { // 2. 如果是岛屿，就将其上下左右都为1的岛屿沉没
+        res++
+        overtrun(n, i)
+      }
+    }
+  }
+
+  return res
+}