# 8 ms,15 lines concise DFS solution[c++]

• ``````int coinChange(vector<int>& coins, int amount) {
sort(coins.begin(),coins.end());
return coinChange(coins,amount,coins.size()-1,0,*(new int(INT_MAX)));
}
int coinChange(vector<int>&coins,int amount,int idx,int cur,int &cand){
if(!amount)return cand=cur;
if(idx<0)return -1;
int flag=0,n=amount/coins[idx];
if(n+cur>=cand)return -1;
for(int i=n;i>=0;i--){
if(coinChange(coins,amount-i*coins[idx],idx-1,cur+i,cand)!=-1) flag=1;
}
if(flag) return cand;
return -1;
}``````

• My code uses the same concept as yours, except I don't return minimum directly. Why it takes 402ms? Could you please take a look for me? Thanks.

``````class Solution {
public:

int coinChange(vector<int>& coins, int amount) {
int Min = amount; //assume one is the smallest coin
//here is an example of using big coins not always to be the best
//  coin:{9, 8, 1},  target 32
int count = 0;
int maxCoinIndex = 0;
unordered_map<int, int> table;
sort(coins.begin(), coins.end(), greater<int>());
if( -1 != coinChange(coins, maxCoinIndex, amount, count, Min))
return Min;
return -1;
}
//if use table, every place that returns must record
int coinChange(vector<int>& coins, int maxCoinIndex, int amount, int count, int& Min)
{

int maxCoin = coins[maxCoinIndex];
int temp = amount/maxCoin;
if(temp+count > Min) {
return -1;
}
if(amount%maxCoin == 0)
{
Min = min(Min, temp+count);
return temp;
} else// not dividable
{
if(maxCoinIndex == coins.size()-1) {
return -1;
}
int localMin = amount+count;
bool noWay = true;
int deduct = 0;
for(int i=0; deduct < amount; ++i, deduct += maxCoin)
{
if (count+i > Min) {
return -1;}
int temp = coinChange(coins, maxCoinIndex+1, amount - deduct, count+i,  Min);
if(temp == -1)
{
continue;
} else
{
localMin = min(localMin, i + temp);
noWay = false;
}
}
if(noWay){
return -1;
}
Min = min(Min, localMin+count);
return localMin;
}
}
};``````

• This post is deleted!

• @quesder I have viewed your code and we have almost the same idea.But I think your code lack some integration,which may cause your algorithm to do too much unnecessary computing for each iteration.You can just simplify your code.

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