53 lines
1.1 KiB
Java
53 lines
1.1 KiB
Java
package com.raorao.leetcode;
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/**
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* 二叉树最短路径.
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*
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* 题目描述：Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along
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* the shortest path from the root node down to the nearest leaf node.
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*
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* @author Xiong Raorao
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* @since 2018-08-07-17:01
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*/
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public class Q1 {
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public static void main(String[] args) {
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}
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/**
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思路：
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递归，若为空树返回0；
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若左子树为空，则返回右子树的最小深度+1；（加1是因为要加上根这一层，下同）
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若右子树为空，则返回左子树的最小深度+1；
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若左右子树均不为空，则取左、右子树最小深度的较小值，+1；
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* @param root
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* @return
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*/
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public int run(TreeNode root) {
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if (root == null) {
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return 0;
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}
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if (root.left == null) {
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return run(root.right) + 1;
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}
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if (root.right == null) {
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return run(root.left) + 1;
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}
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return run(root.left) < run(root.right) ? run(root.left) + 1 : run(root.right) + 1;
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}
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static class TreeNode {
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int val;
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TreeNode left;
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TreeNode right;
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TreeNode(int x) {
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val = x;
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}
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}
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}
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