ACM-ICPC北京赛区2017网络同步赛H

http://hihocoder.com/contest/icpcbeijing2017/problem/8

预处理暴力枚举修改的点

#include <bits/stdc++.h>
using namespace std;
const int maxn = 159;
const int inf = 0x3f3f3f3f;
int a[maxn][maxn];
int colsum[maxn][maxn];
int rowsum[maxn][maxn];
int dp[maxn];
int up[maxn],down[maxn],rig[maxn],lef[maxn];
int main()
{
    int n,m,p;
    while(~scanf("%d%d%d",&n,&m,&p)){
        memset(up,-inf,sizeof(up));
        memset(down,-inf,sizeof(down));
        memset(rig,-inf,sizeof(rig));
        memset(lef,-inf,sizeof(lef));
        for(int i=1;i<=n;i++){
            for(int j=1;j<=m;j++){
                scanf("%d",&a[i][j]);
                colsum[i][j] = colsum[i-1][j]+a[i][j];
                rowsum[i][j] = rowsum[i][j-1]+a[i][j];
            }
        }
        int ans = -inf;
        for(int i=1;i<=n;i++){
            for(int j=i;j<=n;j++){
                dp[0] = -inf;
                for(int k=1;k<=m;k++){
                    int tmp  =colsum[j][k]-colsum[i-1][k];
                    dp[k] = max(dp[k-1]+tmp,tmp);
                    ans = max(ans,dp[k]);
                    lef[k] = max(lef[k],dp[k-1]);
                }
            }
        }
        for(int i=1;i<=n;i++){
            for(int j=i;j<=n;j++){
                dp[m+1] = -inf;
                for(int k=m;k>=1;k--){
                    int tmp  =colsum[j][k]-colsum[i-1][k];
                    dp[k] = max(dp[k+1]+tmp,tmp);
                    rig[k] = max(rig[k],dp[k+1]);
                }
            }
        }
        for(int i=1;i<=m;i++){
            for(int j=i;j<=m;j++){
                dp[0] = -inf;
                for(int k=1;k<=n;k++){
                    int tmp  =rowsum[k][j]-rowsum[k][i-1];
                    dp[k] = max(dp[k-1]+tmp,tmp);
                    up[k] = max(up[k],dp[k-1]);
                }
            }
        }
        for(int i=1;i<=m;i++){
            for(int j=i;j<=m;j++){
                dp[n+1] = -inf;
                for(int k=n;k>=1;k--){
                    int tmp  =rowsum[k][j]-rowsum[k][i-1];
                    dp[k] = max(dp[k+1]+tmp,tmp);
                    down[k] = max(down[k],dp[k+1]);
                }
            }
        }
        for(int i=1;i<=m;i++){
            lef[i] = max(lef[i],lef[i-1]);
        }
        for(int i=m;i>=1;i--){
            rig[i] = max(rig[i],rig[i+1]);
        }
        for(int i=1;i<=n;i++){
            up[i] = max(up[i],up[i-1]);
        }
        for(int i=n;i>=1;i--){
            down[i] = max(down[i],down[i+1]);
        }
        int ret = ans;
        for(int i=1;i<=n;i++){
            for(int j=1;j<=m;j++){
                int tmp = max(up[i],down[i]);
                tmp  = max(tmp,lef[j]);
                tmp = max(tmp,rig[j]);
                tmp = max(tmp,ans-a[i][j]+p);
                ret = min(ret,tmp);
            }
        }
        printf("%d\n",ret);
    }
    return 0;
}
/*
1 4 -1
3 -2 5 9
*/