D. Table with Letters 2 夜

http://codeforces.com/contest/253/problem/D

挺麻烦的一道题

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<map>
#include<vector>
#include<stack>
#include<queue>
#include<algorithm>
#define LL long long
using namespace std;
const int INF=0x3f3f3f3f;
const int N=405;
int sum[N][N];
char s[N][N];
int level[N];
int n,m,k;
LL ans;
bool OK(int x1,int y1,int x2,int y2)
{
    if(x1==x2)
    return true;
    int tmp=sum[x2][y2]-sum[x2][y1-1]-sum[x1-1][y2]+sum[x1-1][y1-1];
    if(tmp<=k)
    return true;
    return false;
}
void Fsearch(char w)
{//cout<<w<<endl;
     for(int j1=1;j1<=m;++j1)
     for(int j2=j1+1;j2<=m;++j2)
     {
         int I=0;
         for(int i=1;i<=n;++i)
         {
             if(s[i][j1]==w&&s[i][j2]==w)
             level[I++]=i;
         }
         int l=0;
         int r=1;
         while(r<I)
         {
             if(OK(level[l],j1,level[r],j2))
             {
                 ans+=(r-l);
                 ++r;
             }
             else
             {
                 ++l;
             }
         }
     }
}
int main()
{
    //freopen("data.in","r",stdin);
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    while(scanf("%d %d %d",&n,&m,&k)!=EOF)
    {
        getchar();
        memset(sum,0,sizeof(sum));
        bool had[27];
        memset(had,false,sizeof(had));
        for(int i=1;i<=n;++i)
        gets(s[i]+1);
        for(int i=1;i<=n;++i)
        for(int j=1;j<=m;++j)
        {
            had[s[i][j]-'a']=true;
            if(s[i][j]=='a')
            sum[i][j]=1;
        }
        for(int i=1;i<=n;++i)
        for(int j=1;j<=m;++j)
        {
            sum[i][j]+=(sum[i-1][j]+sum[i][j-1]-sum[i-1][j-1]);
        }
        ans=0;
        for(char w='a';w<='z';++w)
        if(had[w-'a'])
        Fsearch(w);
        printf("%I64d\n",ans);
    }
    return 0;
}