Hello.I was going through the problem Coin Combinations I which is similar to the next question Coin Combinations II.In Coin Combination II problem I used 2d array to store the dp values and used bottom up approach to solve it.The submission is here.Now I was wondering if Coin Combination I has the similar solution like II using 2d array ? I have gone through many solutions but none of these have used 2d array.So I could not come up with any idea.Please help me with this.
#include<bits/stdc++.h>
using namespace std;
const int mod = 1e9+7;
int main()
{
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n,sum;
cin>>n>>sum;
vector<int>v(n);
for(int i=0;i<n;++i)
{
cin>>v[i];
}
int dp[n+1][sum+1];
memset(dp,0,sizeof(dp));
dp[0][0]=1;
for(int i=1;i<=n;++i)
{
for(int j=0;j<=sum;++j)
{
if(j>=v[i-1])
{
//Condition
dp[i][j]%=mod;
}
}
}
cout<<dp[n][sum]<<endl;
return 0;
}
might be useful: https://codeforces.me/blog/entry/80064
I told it before , if it is possible to use 2d array here to solve it.If not then why?I have already solve it using 1d array
my bad.
How exactly do you want to use a 2d array?
If you do something like dp[n + 1][sum + 1]
That will give you the number of ways of getting a sum $$$s(1 <= s <= n)$$$ from the first i values
So you aren't going to count all the distinct ways
You will count each way just once
For the sample input in the problem, you will have
2 + 2 + 5 = 9
3 + 3 + 3 = 9
2 + 2 + 2 + 3 = 9
And that's just 3 ways