29 lines
778 B
JavaScript
29 lines
778 B
JavaScript
/**
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* Definition for a binary tree node.
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* function TreeNode(val) {
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* this.val = val;
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* this.left = this.right = null;
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* }
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*/
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/**
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* @param {TreeNode} root
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* @return {number[]}
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*/
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export const rightSideView = function (root) {
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if (!root) return []
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const queue = [root] // 队列 把树顶加入队列
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const arr = [] // 用来存储每层最后个元素值
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while (queue.length > 0) {
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let len = queue.length
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while (len) {
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const node = queue.shift() // 取出队列第一个元素
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if (len === 1) arr.push(node.val) // 当是 当前一层的最后一个元素时，把值加入arr
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if (node.left) queue.push(node.left) // 继续往队列添加元素
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if (node.right) queue.push(node.right)
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len--
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}
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}
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return arr
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}
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