[P3933][洛谷10月月赛R2·浴谷八连测R3 -Chtholly-]Chtholly Nota Seniorious

原题链接

题目看起来好麻烦
一开始都没读懂题意
实际上是个二分+贪心
二分一个最大的差值
check的时候按照贪心
然后
因为贪心
还要把图旋转四次才能得到真正的结果

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#include<cstdlib>#include<climits>#include<queue>#define LL long longusing namespace std;int lin[2005],a[2005][2005][5],maxn,minn,n[5],m[5],l,r,mid,ans;bool check(int x,int nico){    int i,j;    lin[0]=m[nico];    for(i=1;i<=n[nico];i++)    {        for(j=1;j<=lin[i-1];j++)            if(maxn-a[i][j][nico]>x) break;        lin[i]=j-1;    }    for(i=1;i<=n[nico];i++)        for(j=lin[i]+1;j<=m[nico];j++)            if(a[i][j][nico]-minn>x) return 0;          return 1;}void gulu(int p1,int p2){    int i,j;    for(i=1;i<=n[p1];i++)        for(j=1;j<=m[p1];j++)            a[j][n[p1]-i+1][p2]=a[i][j][p1];    n[p2]=m[p1];m[p2]=n[p1];}int main(){    int i,j;    scanf("%d%d",&n[1],&m[1]);    minn=2000000000;    for(i=1;i<=n[1];i++)        for(j=1;j<=m[1];j++)        {            scanf("%d",&a[i][j][1]);            maxn=max(maxn,a[i][j][1]);            minn=min(minn,a[i][j][1]);                  }    gulu(1,2);gulu(2,3);gulu(3,4);      l=0;r=maxn-minn;    while(l<=r)    {        mid=(l+r)>>1;        if(check(mid,1)||check(mid,2)||check(mid,3)||check(mid,4)) r=mid-1;        else l=mid+1;    }    printf("%d",l);    return 0;}