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Depth.java
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141 lines (123 loc) · 3.58 KB
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package com.tree;
import java.util.ArrayDeque;
import java.util.Queue;
public class Depth {
/**
* 树的高度-使用递归实现
* @param treeNode
* @return
*/
public static int maxDepth(TreeNode treeNode){
if(treeNode == null){
return 0;
}
int left = maxDepth(treeNode.left);
int right = maxDepth(treeNode.right);
int result = Math.max(left,right) + 1;
return result;
}
/**
* 非递归形式求树的高度
* @param treeNode
* @return
*/
public static int maxDie(TreeNode treeNode){
if(treeNode == null){
return 0;
}
int level =0 ;
Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
queue.offer(treeNode);
while(!queue.isEmpty()){
level++;
int levelSize = queue.size();
for(int i=0;i<levelSize;i++){
TreeNode node = queue.poll();
if(node.left != null){
queue.offer(node.left);
}
if(node.right != null){
queue.offer(node.right);
}
}
}
return level;
}
/**
* 求最小深度
*
* @param treeNode
* @return
*/
public static int minDepth(TreeNode treeNode){
if(treeNode == null){
return 0;
}
if(treeNode.left == null && treeNode.right == null){
return 1;
}
if(treeNode.left == null && treeNode.right != null){
return minDepth(treeNode.right) + 1;
}
if(treeNode.right == null && treeNode.left != null){
return minDepth(treeNode.left) + 1;
}
int left = minDepth(treeNode.left);
int right = maxDepth(treeNode.right);
return Math.min(left,right) + 1;
}
public static int minDepth2(TreeNode treeNode){
if(treeNode == null){
return 0;
}
int level =0 ;
Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
queue.offer(treeNode);
while(!queue.isEmpty()){
level++;
int levelSize = queue.size();
for(int i=0;i<levelSize;i++){
TreeNode node = queue.poll();
if(node.left == null && node.right == null ){
return level;
}
if(node.left != null){
queue.offer(node.left);
}
if(node.right != null){
queue.offer(node.right);
}
}
}
return 0;
}
public static void main(String[] args) {
TreeNode A = new TreeNode("A");
TreeNode B = new TreeNode("B");
TreeNode C = new TreeNode("C");
TreeNode D = new TreeNode("D");
TreeNode E = new TreeNode("E");
TreeNode F = new TreeNode("F");
TreeNode G = new TreeNode("G");
TreeNode H = new TreeNode("H");
TreeNode I = new TreeNode("I");
TreeNode J = new TreeNode("J");
TreeNode K = new TreeNode("K");
A.left = B;
A.right = C;
B.left = D;
B.right = E;
D.left = H;
D.right = I;
E.right = J;
C.left = F;
C.right = G;
F.right = K;
Depth depth = new Depth();
System.out.println("depth = " + maxDepth(A));
System.out.println("depth = " + maxDie(A));
System.out.println("depth = " + minDepth(A));//有问题
System.out.println("depth = " + minDepth2(A));
//4 4 3 3
}
}