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codeforce Gym 101102A Coins (01背包变形)

  01背包变形,注意dp过程的时候就需要取膜,否则会出错。

  代码如下:

#include<iostream>#include<cstdio>#include<cstring>using namespace std;#define MAXW 15005#define N 155#define LL long long#define MOD 1000000007int w1[N],w2[N];LL dp1[MAXW],dp2[MAXW];int main(){//    freopen("A.in.cpp","r",stdin);    int t,n,m,k,W,s,e;    int sum1,sum2;    LL ans;    cin>>t;    while(t--)    {        cin>>n>>m>>k>>W;        sum1 = sum2 = 0;        for(int i = 0; i < n; i++)        {            cin>>w1[i];            sum1 += w1[i];        }        for(int i = 0; i < m; i++)        {            cin>>w2[i];            sum2 += w2[i];        }        memset(dp1,0,sizeof(dp1));        memset(dp2,0,sizeof(dp2));        dp1[0] = dp2[0] = 1;        for(int i = 0; i < n; i++)        {            for(int j = sum1; j >= w1[i]; j--)            {                dp1[j] = (dp1[j]%MOD + dp1[j-w1[i]]%MOD)%MOD;///没有mod就wa            }        }        for(int i = 0; i < m; i++)        {            for(int j = sum2; j >= w2[i]; j--)            {                dp2[j] = (dp2[j]%MOD + dp2[j-w2[i]]%MOD)%MOD;            }        }        if((W-k)%2 != 0) s = (W-k)/2+1;        else s = (W-k)/2;        e = W-s;        ans = 0;        for(int i = s; i <= e; i++)        {            ans = (((dp1[i]%MOD)*(dp2[W-i]%MOD))%MOD + ans%MOD) % MOD;        }        cout<<ans<<endl;    }    return 0;}

 

codeforce Gym 101102A Coins (01背包变形)