洛谷P3444 [POI2006]ORK-Ploughing [枚举，贪心]

　　题目传送门

ork

格式难调，题面就不放了。

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　　分析：

　　一道偏难的贪心和枚举题。考试的时候是弃疗了。。。yyb巨佬已经讲的很详细了，推荐他的博客。这里小蒟蒻就只放代码了。

　　Code：

#include<bits/stdc++.h>
using namespace std;
const int N=;
int n,m,K,a[N][N],ans=1e9;
int sx[N][N],sy[N][N];
inline int read()
{
    char ch=getchar();int num=;bool flag=false;
    while(ch<''||ch>''){if(ch=='-')flag=true;ch=getchar();}
    while(ch>=''&&ch<=''){num=num*+ch-'';ch=getchar();}
    return flag?-num:num;
}
inline int workup(int up)
{
    int x1=,x2=n,y1=,y2=m,ret=,ka;
    while(x1<=x2&&y1<=y2){
        ret++;
        ka=sy[x2][y1]-sy[x1-][y1];
        if(ka<=K){++y1;continue;};
        ka=sy[x2][y2]-sy[x1-][y2];
        if(ka<=K){--y2;continue;}
        ka=sx[x1][y2]-sx[x1][y1-];
        if(ka<=K&&x1<up){++x1;continue;}
        ka=sx[x2][y2]-sx[x2][y1-];
        if(ka<=K){--x2;continue;}
        ret=1e9;break;
    }
    return ret;
}
inline int workle(int left)
{
    int x1=,x2=n,y1=,y2=m,ret=,ka;
    while(x1<=x2&&y1<=y2){
        ret++;
        ka=sx[x1][y2]-sx[x1][y1-];
        if(ka<=K){++x1;continue;}
        ka=sx[x2][y2]-sx[x2][y1-];
        if(ka<=K){--x2;continue;}
        ka=sy[x2][y1]-sy[x1-][y1];
        if(ka<=K&&y1<left){++y1;continue;}
        ka=sy[x2][y2]-sy[x1-][y2];
        if(ka<=K){--y2;continue;}
        ret=1e9;break;
    }
    return ret;
}
int main()
{
    //freopen("ork.in","r",stdin);
    //freopen("ork.out","w",stdout);
    K=read();m=read();n=read();
    for(int i=;i<=n;i++)
    for(int j=;j<=m;j++)
    a[i][j]=read();
    for(int i=;i<=n;i++)
    for(int j=;j<=m;j++){
    sx[i][j]=sx[i][j-]+a[i][j];
    sy[i][j]=sy[i-][j]+a[i][j];}
    for(int i=;i<=n;i++)
    ans=min(ans,workup(i));
    for(int j=;j<=m;j++)
    ans=min(ans,workle(j));
    printf("%d\n",ans);
    return ;
}