2018焦作网络赛B

Posted 2021-01-06 lmissher

dp维护一下最大值与最小值，注意边界情况的判定。

 

 

 

#include <iostream>
#include <cstring>

using namespace std;

const long long inf = (long long)1e18+(long long)9;
long long dp[7][1005];
long long dpx[7][1005];
int f[1005];
char s[15];

int main()
{
    int T;
//    int l;
    int n,m;
    long long k;
    long long ans;
    scanf("%d",&T);
    while(T--)
    {
        memset(dp,0,sizeof(dp));
        memset(dpx,0,sizeof(dpx));
        scanf("%d%d%lld",&n,&m,&k);
        for(int i=0;i<=m;i++)
        for(int j=0;j<=n;j++)
        {
            dp[i][j]=-inf;
            dpx[i][j]=inf;
        }
        for(int i=1;i<=n;i++)
        scanf("%d",&f[i]);
        getchar();
        scanf("%s",s);
        //for(int i=0;i<=m;i++)
        dpx[0][0]=dp[0][0]=k;
        ans=-inf;
        for(int i=1;i<=n;i++)
        {
            dpx[0][i]=dp[0][i]=k;
            for(int j = 0; j < m; j++)
            {
                dp[j+1][i]=-inf;
                dpx[j+1][i]=inf;
                if(j+1<=i-1)
                {
                    dp[j+1][i]=max(dp[j+1][i],dp[j+1][i-1]);
                    dpx[j+1][i]=min(dpx[j+1][i],dpx[j+1][i-1]);
                }
                //if(i<=j)continue;
                if(s[j]==‘+‘)
                {
                    dp[j+1][i]=max(dp[j+1][i],dp[j][i-1]+f[i]);
                    //dp[j+1][i]=max(dp[j+1][i],dpx[j][i-1]+f[i]);
                    //dpx[j+1][i]=min(dpx[j+1][i],dp[j][i-1]+f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dpx[j][i-1]+f[i]);
                }
                if(s[j]==‘-‘)
                {
                    dp[j+1][i]=max(dp[j+1][i],dp[j][i-1]-f[i]);
                    //dp[j+1][i]=max(dp[j+1][i],dpx[j][i-1]-f[i]);
                    //dpx[j+1][i]=min(dpx[j+1][i],dp[j][i-1]-f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dpx[j][i-1]-f[i]);
                }
                if(s[j]==‘*‘)
                {
                    dp[j+1][i]=max(dp[j+1][i],dp[j][i-1]*f[i]);
                    dp[j+1][i]=max(dp[j+1][i],dpx[j][i-1]*f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dp[j][i-1]*f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dpx[j][i-1]*f[i]);
                }
                if(s[j]==‘/‘&&f[i]!=0)
                {
                    dp[j+1][i]=max(dp[j+1][i],dp[j][i-1]/f[i]);
                    dp[j+1][i]=max(dp[j+1][i],dpx[j][i-1]/f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dp[j][i-1]/f[i]);
                    dpx[j+1][i]=min(dpx[j+1][i],dpx[j][i-1]/f[i]);
                }
                if(j==m-1&&dp[j+1][i]>ans&&dp[j+1][i]!=inf&&j+1<=i)
                {
                    //cout<<i<<‘ ‘<<j<<‘ ‘<<dp[j+1][i]<<endl;
                    ans=dp[j+1][i];
                }
            }
        }
        if(ans==inf || ans==-inf)
        ans =k;
        //for()
        printf("%lld
",ans);
    }
    return 0;
}
//0 1 2 3 4 5

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