uva10593 Kites(DP)

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int n;
char s[502][502];
int dp1[502][502],dp2[502][502];
int DP1(int x,int y){
    if(s[x][y]==‘.‘) return 0;
    if(x==0||y==0) return s[x][y]==‘x‘ ? 1:0;
    if(dp1[x][y]!=-1) return dp1[x][y];
    int ret=1000;
    ret=min(ret,DP1(x-1,y));
    ret=min(ret,DP1(x,y-1));
    if(s[x-ret][y-ret]==‘x‘) return dp1[x][y]=ret+1;
    else return dp1[x][y]=ret;
}
int DP2(int x,int y){
    if(s[x][y]==‘.‘) return 0;
    if(x==0||y==0||y==n-1||s[x-1][y]==‘.‘) return s[x][y]==‘x‘ ? 1:0;
    if(dp2[x][y]!=-1) return dp2[x][y];
    int ret=1000;
    ret=min(ret,DP2(x-1,y-1));
    ret=min(ret,DP2(x-1,y+1));
    if(x-2*ret>=0){
        if(s[x-2*ret][y]==‘x‘&&s[x-2*ret+1][y]==‘x‘) return dp2[x][y]=ret+1;
    }
    return dp2[x][y]=max(ret,1);
}
int main(){
    while(~scanf("%d",&n)){
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                cin>>s[i][j];
            }
        }
        memset(dp1,-1,sizeof dp1);
        memset(dp2,-1,sizeof dp2);
        int ans=0;
        for(int i=n-1;i>=0;i--){
            for(int j=n-1;j>=0;j--){
                if(s[i][j]==‘x‘){
                    ans+=DP1(i,j)-1+DP2(i,j)-1;
                }
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}