对二维数组排序

class Solution {
public:
static bool cmp(vector<int> &a, vector<int> &b) {return a[1]<b[1];}
    int findLongestChain(vector<vector<int>>& pairs) {
        if(pairs.size()==0) return 0;
        sort(pairs.begin(),pairs.end(),cmp);

        int end = pairs[0][1];
        int ans=1;
        for(int i=1;i<pairs.size();i++){
            if(pairs[i][0]>end){
                end = pairs[i][1];
                ans++;
            }
        }

        return ans;

    }
};