[动态规划] leetcode 354 Russian Doll Envelopes

Posted 2022-06-27 fish1996

problem:https://leetcode.com/problems/russian-doll-envelopes/

        最长连续子序列类型问题。先排序，dp[i]记录使用第i个套娃的最大数量。

bool cmp(const vector<int>& x, const vector<int>& y)

    return x[0] == y[0] ? x[1] < y[1] : x[0] < y[0];

class Solution 
public:

    int maxEnvelopes(vector<vector<int>>& envelopes) 
        sort(envelopes.begin(), envelopes.end(), cmp);
        int n = envelopes.size();
        if(!n) return 0;
        vector<int> dp(n, 1);
        int res = 0;
        for(int i = 0;i < n;i++)
        
            for(int j = 0;j < i;j++)
            
                if(envelopes[j][0] == envelopes[i][0]) break;
                if(envelopes[i][1] > envelopes[j][1])
                
                    dp[i] = max(dp[i], dp[j] + 1);
                
            
            res = max(dp[i], res);
        
        return res;
    
;