https://leetcode.com/contest/weekly-contest-61/problems/delete-and-earn/

class Solution {
public:
    int deleteAndEarn(vector<int>& nums) {
        if (nums.size() == 0) return 0;
        std::sort(nums.begin(), nums.end());
        int count = 1;
        int now = nums[0];
        vector<pair<int,int>> v;
        for (int i = 1; i < nums.size(); i++) {
            if (now != nums[i]) {
                v.push_back(make_pair(now, count));
                now =  nums[i];
                count = 1;
            } else {
                count++;
            }
        }
        v.push_back(make_pair(now, count));

        vector<int> answer(v.size(), 0);
        answer[0] = (v[0].first * v[0].second);
        int score_with;
        for (int i = 1; i < v.size(); i++) {
            if (v[i].first == (v[i - 1].first + 1)) {
                score_with = (v[i].first * v[i].second) + ((i > 1) ? (answer[i - 2]) : (0));
            } else {
                score_with = (v[i].first * v[i].second) + (answer[i - 1]);
            }
            answer[i] = ((score_with > answer[i - 1]) ? score_with : answer[i - 1]);
        }
        return answer[v.size() - 1];
    }
};