646.maximum-length-of-pair-chain.cpp

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