Create 968-binary-tree-cameras.js

Author: everthis

968-binary-tree-cameras.js

@@ -0,0 +1,27 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+const minCameraCover = function(root) {
+  if (root === null) return 0;
+  let max = 0;
+  return (helper(root) < 1 ? 1 : 0) + max;
+  function helper(root) {
+    if (root === null) return 2;
+    if (root.left === null && root.right === null) return 0;
+    let left = helper(root.left);
+    let right = helper(root.right);
+    if (left === 0 || right === 0) {
+      max++;
+      return 1;
+    }
+    return left === 1 || right === 1 ? 2 : 0;
+  }
+};