LC 465. Optimal Account Balancing
A group of friends went on holiday and sometimes lent each other money. For example,Alice paid for Bill‘s lunch for $10. Then later Chris gave Alice $5 for a taxi ride. We can model each transaction as a tuple (x,y,z) which means person x gave person y $z. Assuming Alice,Bill,and Chris are person 0,1,and 2 respectively (0,2 are the person‘s ID),the transactions can be represented as? Given a list of transactions between a group of people,return the minimum number of transactions required to settle the debt. Note:
? Example 1: Input:
[[0,5]]
Output:
2
Explanation:
Person #0 gave person #1 $10.
Person #2 gave person #0 $5.
Two transactions are needed. One way to settle the debt is person #1 pays person #0 and #2 $5 each.
? Example 2: Input: [[0,[1,1],5],5]] Output: 1 Explanation: Person #0 gave person #1 $10. Person #1 gave person #0 $1. Person #1 gave person #2 $5. Person #2 gave person #0 $5. Therefore,person #1 only need to give person #0 $4,and all debt is settled. class Solution { public: int minTransfers(vector<vector<int>>& transactions) { map<int,int> m; for(auto t: transactions){ m[t[0]] -= t[2]; m[t[1]] += t[2]; } vector<int> accnt(m.size()); int cnt = 0; for(auto a : m){ if(a.second != 0) accnt[cnt++] = a.second; } return helper(accnt,0,cnt,0); } int helper(vector<int>& accnt,int start,int n,int num){ int ret = INT_MAX; while(start < n && accnt[start] == 0) start++; for(int i=start+1; i<n; i++){ if((accnt[start] < 0 && accnt[i] > 0) || (accnt[start] > 0 && accnt[i] < 0)){ accnt[i] += accnt[start];//加入第i个账户中,这个时候start账户已经没有钱了,可以进行下一个账户清理了 ret = min(ret,helper(accnt,start+1,n,num+1));//DFS,保存最小值 accnt[i] -= accnt[start]; } } return ret == INT_MAX ? num : ret; } }; (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |