mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
91 lines
2.5 KiB
C++
91 lines
2.5 KiB
C++
#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <algorithm>
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#include <iostream>
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#include <vector>
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#define MAXN 505
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#define INF 1000000007
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using namespace std;
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const int dir[4][2]={{1,1},{-1,1},{1,-1},{-1,-1}};
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int n, m,ans;
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int dp[MAXN][MAXN][4],to[4]={3,2,1,0};
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char st[MAXN][MAXN];
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long long p[MAXN], r[MAXN][MAXN], c[MAXN][MAXN];
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void cal(int x,int y,int k)
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{
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int now=dp[x][y][k];
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x+=dir[k][0],y+=dir[k][1];
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while(x>=0&&x<n&&y>=0&&y<m)
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{
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if(dp[x][y][to[k]]<=now) now=dp[x][y][to[k]];
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else if(dp[x][y][to[k]]>=now+2)
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now+=2;
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else ++now;
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ans=max(now,ans);
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x+=dir[k][0],y+=dir[k][1];
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}
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}
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long long ac1(int rr,int x,int y)
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{
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int l=y-x+1;
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if (!x) return r[rr][y];
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return r[rr][y]-r[rr][x-1]*p[l];
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}
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long long ac2(int cc,int x,int y)
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{
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int l=y-x+1;
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if (!x) return c[cc][y];
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return c[cc][y]-c[cc][x-1]*p[l];
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}
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int main()
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{
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int cas;
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scanf("%d",&cas);
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p[0]=1;
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for (int i=1;i<=500;i++) p[i]=p[i-1]*131;
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while (cas--)
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{
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ans=1;
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scanf("%d%d",&n,&m);
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for (int i=0;i<n;i++)
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scanf("%s",st[i]);
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for (int i=0;i<n;i++)
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{
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r[i][0]=st[i][0];
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for (int j=1;j<m;j++)
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r[i][j]=r[i][j-1]*131+st[i][j];
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}
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for (int i=0;i<m;i++)
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{
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c[i][0]=st[0][i];
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for (int j=1;j<n;j++)
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c[i][j]=c[i][j-1]*131+st[j][i];
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}
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for(int i=0;i<n;++i)
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for(int j=0;j<m;++j)
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for(int k=0;k<4;++k)
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{
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int a=k&1?i+1:n-i,b=k<2?m-j:j+1,l=0,r,mid,nx,ny,x2,y2;
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r=min(a-1,b-1);
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while(l<r)
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{
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mid=(l+r+1)/2;
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nx=i+mid*dir[k][0],ny=j+mid*dir[k][1];
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x2=i,y2=j;
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if(x2<nx) swap(x2,nx);
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if(y2<ny) swap(y2,ny);
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if(ac1(i,ny,y2)==ac2(j,nx,x2)) l=mid;
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else r=mid-1;
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}
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dp[i][j][k]=l+1;
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}
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for(int i=0;i<m;++i)
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cal(0,i,2),cal(0,i,0),cal(n-1,i,1),cal(n-1,i,3);
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for(int i=0;i<n;++i)
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cal(i,m-1,2),cal(i,m-1,3),cal(i,0,1),cal(i,0,0);
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printf("%d\n",ans*(ans+1)/2);
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}
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return 0;
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}
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