111. Minimum Depth of Binary Tree
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.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3
/ 9 20
/ 15 7
return its minimum depth = 2.
package leetcode.easy;
public class MinimumDepthOfBinaryTree {
@org.junit.Test
public void test() {
TreeNode tn11 = new TreeNode(3);
TreeNode tn21 = new TreeNode(9);
TreeNode tn22 = new TreeNode(20);
TreeNode tn33 = new TreeNode(15);
TreeNode tn34 = new TreeNode(7);
tn11.left = tn21;
tn11.right = tn22;
tn21.left = null;
tn21.right = null;
tn22.left = tn33;
tn22.right = tn34;
tn33.left = null;
tn33.right = null;
tn34.left = null;
tn34.right = null;
System.out.println(minDepth(tn11));
}
public int minDepth(TreeNode root) {
if (null == root) {
return 0;
} else if (null == root.left) {
return 1 + minDepth(root.right);
} else if (null == root.right) {
return 1 + minDepth(root.left);
} else {
return 1 + Math.min(minDepth(root.left), minDepth(root.right));
}
}
}
LeetCode_111. Minimum Depth of Binary Tree
原文：https://www.cnblogs.com/denggelin/p/11617571.html