class Solution {    public int strStr(String haystack, String needle) {        int i = 0, j = 0;        int a = haystack.length();        int b = needle.length();        if(a

 

 

class Solution {    public int strStr(String haystack, String needle) {                if(haystack.length() == 0&&needle.length() != 0) return -1;                int l1=haystack.length();                int l2=needle.length();                boolean flag;                for(int i = 0 ; i <= l1-l2; i++){                    flag = true;                    for(int j = 0 ; j < needle.length() ; j ++) {                        if(haystack.charAt(i+j) != needle.charAt(j)) {                            flag = false;                            break;                        }                    }                    if(flag) return i;                }                return -1;            }    }

 

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } *//*class Solution {    public List
      
       
        > levelOrderBottom(TreeNode root) {        List
        
         
          > res = new ArrayList<>();            if(root == null) return res;            //定义一个队列q            Queue
          
            q = new LinkedList<>();            q.offer(root);//把根加入队列            while(!q.isEmpty()) {                int sz = q.size();                ArrayList
           
             list = new ArrayList<>(); for(int i=0; i
            
              queue=new LinkedList<>(); * 入队：offer * 出队：poll * 得到队头：peek * 大小：size * 空：isEmpty */ public List
             
              
               > levelOrderBottom(TreeNode root) { // write your code here List
               
                
                 > res = new ArrayList<>(); List
                 
                   list = new ArrayList<>(); if(root==null){ return res; } Queue
                  
                    queue = new LinkedList<>(); TreeNode curLast = root; TreeNode nextLast = root; queue.offer(root); while (!queue.isEmpty()){ TreeNode node = queue.poll(); list.add(node.val); if(node.left!=null){ queue.offer(node.left); nextLast = node.left; } if(node.right!=null){ queue.offer(node.right); nextLast = node.right; } if(node==curLast){ curLast = nextLast; res.add(new ArrayList<>(list)); list = new ArrayList<>(); } } Collections.reverse(res); return res; }}