leet面试150

5、最长回文子串

class Solution {
    public String longestPalindrome(String s) {
        if(s==null || s.length()==0) return null;
        char[] ss=s.toCharArray();
        int resi=0,resj=0,reslen=0,len=s.length();
        boolean[][] dp=new boolean[len][len];
        for(int i=len-1;i>=0;--i){      //这里要注意一定是从下到上，从左到右！！！
            for(int j=i;j<len;++j){
                if(ss[i]==ss[j]){
                    if(j-i<=1 || dp[i + 1][j - 1])  //两种情况
                        dp[i][j]=true;
                }
                if(dp[i][j]==true && j-i+1>reslen){
                    resi=i;
                    resj=j;
                    reslen=j-i+1;
                }
            }
        }
        return s.substring(resi,resj+1);
    }
}

7、整数反转

https://leetcode.cn/problems/reverse-integer/

class Solution {
    public int reverse(int x) {
       int res = 0;
       while(x != 0) {
            int temp = res * 10 + x % 10;
            x /= 10;
            if (temp / 10 != res) {  //溢出判断的一个很妙的条件
                return 0;
            }
            res = temp;
       }
       return res; 
    }
}

11、盛水最多的容器

https://leetcode.cn/problems/container-with-most-water/​​​​​​​

class Solution {
    public int maxArea(int[] height) {
        int len=height.length;
        if(len==0) return 0;
        int res=0;
        for(int i=0,j=len-1;i<j;){
            res=Math.max(res,(j-i)*Math.min(height[i],height[j]));
            if(height[i]<height[j]) ++i;
            else --j;
        }
        return res;
    }
}

未完待续！