HDU-4618 Palindrome Sub-Array 暴力枚举

　　题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4618

　　直接暴力枚举中心点，在中间如果求不出最大值直接跳过优化下。。。

//STATUS:C++_AC_31MS_800KB
#include <functional>
#include <algorithm>
#include <iostream>
//#include <ext/rope>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <numeric>
#include <cstring>
#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
#include <bitset>
#include <queue>
#include <stack>
#include <cmath>
#include <ctime>
#include <list>
#include <set>
#include <map>
#pragma comment(linker,"/STACK:102400000,102400000")
using namespace std;
//using namespace __gnu_cxx;
//define
#define pii pair<int,int>
#define mem(a,b) memset(a,b,sizeof(a))
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define PI acos(-1.0)
//typedef
typedef __int64 LL;
typedef unsigned __int64 ULL;
//const
const int N=310,M=2000010;
const int INF=0x3f3f3f3f;
const int MOD=100000,STA=8000010;
const LL LNF=1LL<<60;
const double EPS=1e-8;
const double OO=1e15;
const int dx[4]={-1,0,1,0};
const int dy[4]={0,1,0,-1};
const int day[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
//Daily Use ...
inline int sign(double x){return (x>EPS)-(x<-EPS);}
template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}
template<class T> inline T lcm(T a,T b,T d){return a/d*b;}
template<class T> inline T Min(T a,T b){return a<b?a:b;}
template<class T> inline T Max(T a,T b){return a>b?a:b;}
template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}
template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}
template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}
template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}
//End

int w[N][N];
int T,n,m,ans;

int slove(int x,int y)
{
    int i,j,c,ok,ret=1;
    for(c=ok=1;x-c>=0&&x+c<n && y-c>=0&&y+c<m;c++){
        for(i=0;i<=c;i++){
            if(w[x-c+i][y-c]!=w[x-c+i][y+c]
               || w[x-c][y-c+i]!=w[x+c][y-c+i]
               || w[x+i][y-c]!=w[x-i][y-c]
               || w[x+i][y+c]!=w[x-i][y+c]
               || w[x-c][y-i]!=w[x-c][y+i]
               || w[x+c][y-i]!=w[x+c][y+i]){ok=0;break;}
        }
        if(!ok)break;
    }
    ret=(c-1)<<1|1;
    for(c=ok=1;x-c+1>=0&&x+c<n && y-c+1>=0&&y+c<m;c++){
        for(i=0;i<=c;i++){
            if(w[x-c+i+1][y-c+1]!=w[x-c+i+1][y+c]
               || w[x-c+1][y-c+i+1]!=w[x+c][y-c+i+1]
               || w[x+i][y-c+1]!=w[x-i+1][y-c+1]
               || w[x+i][y+c]!=w[x-i+1][y+c]
               || w[x-c+1][y-i+1]!=w[x-c+1][y+i]
               || w[x+c][y-i+1]!=w[x+c][y+i]){ok=0;break;}
        }
        if(!ok)break;
    }
    return Max(ret,(c-1)<<1);
}

int main()
{
 //   freopen("in.txt","r",stdin);
    int i,j;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&m);
        for(i=0;i<n;i++){
            for(j=0;j<m;j++){
                scanf("%d",&w[i][j]);
            }
        }

        ans=1;
        for(i=0;i<n;i++){
            if( ((i+1)<<1)<=ans || (((n-i-1)<<1)|1)<=ans)continue;
            for(j=0;j<m;j++){
                if( ((j+1)<<1)<=ans || (((m-j-1)<<1)|1)<=ans)continue;
                    ans=Max(ans,slove(i,j));
            }
        }

        printf("%d
",ans);
    }
    return 0;
}