Create 959-regions-cut-by-slashes.js

Author: everthis

959-regions-cut-by-slashes.js

@@ -0,0 +1,34 @@
+/**
+ * @param {string[]} grid
+ * @return {number}
+ */
+const regionsBySlashes = function(grid) {
+  const len = grid.length
+  let regionsNum = 0
+  const dirs = [[-1, 0], [1, 0], [0, 1], [0, -1]]
+  const matrix = Array.from({ length: 3 * len }, () => new Array(3 * len).fill(0))
+
+  // 把每个格子切成3 * 3个小格子，再标记出现线段的位置
+  for (let i = 0; i < len; i++) {
+    for (let j = 0; j < len; j++) {
+      if (grid[i][j] === '/') matrix[i * 3][j * 3 + 2] = matrix[i * 3 + 1][j * 3 + 1] = matrix[i * 3 + 2][j * 3] = 1
+      if (grid[i][j] === '\\') matrix[i * 3][j * 3] = matrix[i * 3 + 1][j * 3 + 1] = matrix[i * 3 + 2][j * 3 + 2] = 1
+    }
+  }
+
+  for (let i = 0; i < matrix.length; i++) {
+    for (let j = 0; j < matrix.length; j++) {
+      if (matrix[i][j] === 0) {
+        dfs(matrix, i, j, dirs)
+        regionsNum++
+      }
+    }
+  }
+  return regionsNum
+}
+function dfs(m, i, j, dirs) {
+  if (i >= 0 && j >= 0 && i < m.length && j < m.length && m[i][j] === 0) {
+    m[i][j] = 1
+    for (let dir of dirs) dfs(m, i + dir[0], j + dir[1], dirs)
+  }
+}