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222.完全二叉树的节点个数.js
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222.完全二叉树的节点个数.js
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/*
* @lc app=leetcode.cn id=222 lang=javascript
*
* [222] 完全二叉树的节点个数
*/
// @lc code=start
/**
* Definition for a binary tree node.
* function TreeNode(val) {
* this.val = val;
* this.left = this.right = null;
* }
*/
/**
* @param {TreeNode} root
* @return {number}
*/
var countNodes = function (root) {
if (!root) {
return 0;
}
let totalLevel = 0;
let head = root;
while (head) {
totalLevel++;
head = head.left;
}
let levelCount = 1;
let i = 0;
let sum = 0;
while (i < totalLevel) {
sum += levelCount;
levelCount = levelCount * 2;
i++;
}
let stack = [{ index: 1, node: root, level: 1 }];
let flag = false;
let fn = (right) => {
fn = () => null;
return right !== null;
}
while (stack.length) {
debugger;
let {
node: { left, right },
index,
level,
} = stack.shift();
if (level === totalLevel - 1 && fn(right)) {
return sum;
}
if (right === null) {
// console.log(index, level);
flag = true;
}
if (flag && level >= totalLevel - 1 && (left || right)) {
return sum - (2 ** level - index * 2 + (right ? 0 : 1));
}
left &&
stack.unshift({ node: left, index: index * 2 - 1, level: level + 1 });
right && stack.unshift({ node: right, index: index * 2, level: level + 1 });
}
return sum;
};
// @lc code=end
function TreeNode(val) {
this.val = val;
this.left = this.right = null;
}
const a = new TreeNode(1);
const b = new TreeNode(2);
const c = new TreeNode(3);
const d = new TreeNode(4);
const e = new TreeNode(5);
const f = new TreeNode(6);
const g = new TreeNode(7);
c.left = f;
// c.right = g;
b.left = d;
b.right = e;
a.left = b;
a.right = c;
// d.left = new TreeNode(8);
console.log(countNodes(a));