646. Maximum Length of Pair Chain

You are given n pairs of numbers. In every pair, the first number is always smaller than the second number.

Now, we define a pair (c, d) can follow another pair (a, b) if and only if b < c. Chain of pairs can be formed in this fashion. 

Given a set of pairs, find the length longest chain which can be formed. You needn‘t use up all the given pairs. You can select pairs in any order.

Example 1:

Input: [[1,2], [2,3], [3,4]]
Output: 2
Explanation: The longest chain is [1,2] -> [3,4]

class Solution {
public:
    int findLongestChain(vector<vector<int>>& pairs) {
        sort(pairs.begin(),pairs.end());
        int n = pairs.size();
        vector<int>dp(n,1);
        int maxLen = 1;
        for(int i=1;i<n;i++)
        {
            for(int j=0;j<i;j++)
            {
                if(pairs[i][0]>pairs[j][1])
                    dp[i] = max(dp[i],dp[j]+1);
            }
            maxLen = max(maxLen,dp[i]);
        }
        return maxLen;
    }
};