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Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
思路:求解根节点到叶子的最小距离。与求树的最大深度类似,只是一个求大,一个求小。具体代码如下:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int minDepth(TreeNode root) {
if(root == null)
return 0;
return minDep(0,root);
}
private int minDep(int dep,TreeNode root){
if(root == null){
return dep;
}
int dep1 = minDep(dep+1,root.left);
int dep2 = minDep(dep+1,root.right);
if(dep1 == dep+1){
return dep2;
}
if(dep2 == dep+1){
return dep1;
}
return dep1 > dep2 ? dep2 : dep1;
}
}