<JZOJ5938>分离计划

emm骚操作

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#define rint register int
#define max(a,b) (a>b?a:b)
#define min(a,b) (a<b?a:b)
#define swap(a,b) (a^=b,b^=a,a^=b)
template <class T>inline void read(T &X)
{
    X=0;int W=0;char ch=0;
    while(!isdigit(ch))W|=ch=='-',ch=getchar();
    while(isdigit(ch))X=(X<<3)+(X<<1)+(ch^48),ch=getchar();
    X=W?-X:X;return;
}
int n,m,a[2010][2010],ma=-1,mi=99999999,ans=999999999;
void turn()
{
    for(rint i=1;i<=n;++i)
        for(rint j=1;j<=m/2;++j)
            swap(a[i][j],a[i][m-j+1]);
}
void down()
{
    for(rint i=1;i<=n/2;++i)
        for(rint j=1;j<=m;++j)
            swap(a[i][j],a[n-i+1][j]);
}

int check(int x)
{
    int to=m+1;
    for(rint i=1;i<=n;++i)
    {
        int t=0;
        for(rint j=1;j<=min(to,m);++j)
            if(ma-a[i][j]<=x)t=max(t,j);
            else break;
        to=t;
        for(rint j=t+1;j<=m;++j)
            if(a[i][j]-mi>x)return 0;
    }
    return 1;
}

int sep()
{
    int l=1,r=ma-mi+1;
    while(l<=r)
    {
        int mid=l+r>>1;
        if(check(mid))r=mid-1;
        else l=mid+1;
    }
    return l;
}
int main()
{
    freopen("separate.in","r",stdin);
    freopen("separate.out","w",stdout);
    read(n),read(m);
    for(rint i=1;i<=n;++i)
        for(rint j=1;j<=m;++j)
        {
            read(a[i][j]);
            ma=max(ma,a[i][j]);
            mi=min(mi,a[i][j]);
        }
    ans=min(ans,sep());
    turn();
    ans=min(ans,sep());
    down();
    ans=min(ans,sep());
    turn();
    ans=min(ans,sep());
    printf("%d\n",ans);
return 0;
}