双指针法

class Solution {
public:
    vector> intervalIntersection(vector>& firstList, vector>& secondList) {
        vector< vector > res;
        int i=0,j=0;
        while(i 
844. 比较含退格的字符串 
class Solution {
public:
    bool backspaceCompare(string s, string t) {
		int num1=0,num2=0;
		int i=s.size()-1,j=t.size()-1;
		while(i>=0||j>=0){
			while(i>=0){
				if(s[i]=='#'){
					num1++;
					i--;
				}
				else if(num1>0){//若num不为0得抵消掉前面一个字母
					num1--;
					i--;
				}
				else break;
			} 
			while(j>=0){
				if(t[j]=='#'){
					num2++;
					j--;
				}
				else if(num2>0){
					num2--;
					j--;
				}
				else break;
			} 
			if(i>=0&&j>=0){
                if(s[i]!=t[j]){
                    return 0;
                }
            } 
			else{
                if(i>=0||j>=0){
                    return 0;
                }
            }
            i--;
			j--;
		}
		return 1;
    }
};
 
盛最多水的容器 
class Solution {
public:
    int maxArea(vector& height) {
		int i=0;
		int j=height.size()-1;
		int ans=0;
		while(i