【Greedy】646. Maximum Length of Pair Chain

按照尾部从小到大排序：

class Solution {
public:
    int findLongestChain(vector<vector<int>>& pairs) {
       
        sort(pairs.begin(),pairs.end(),cmp);
        int ans=1,flag=0;
        for(int i =1;i<pairs.size();i++)
        {
            if(pairs[i][0]>pairs[flag][1])
            {
                flag=i;
                ans++;
            }
        }
        return ans;
    }
    bool static cmp(vector<int> &A, vector<int> &B)
    {
        return A[1]<B[1];
    }
};