E1 - the white knight, WA

WA, on problem: http://www.codechef.com/problems/E1 my code: http://ideone.com/OWMH40

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int main() {
    int t, n, a[1010][1010], x, y;
    char s[1000];
    scanf("%d", &t);
    while(t--) {
        memset(a, 0, sizeof(a));
        scanf("%d", &n);
        for(int i=0; i<n; i++) {
            scanf("%s", s);
            for(int j=0; j<n; j++) {
                if(s[j]=='P') a[i+5][j+5]++;
                else if(s[j]=='K') x=i+5, y=j+5;
            }
        }
        for(int j=n+4; j>=y; j--) {
            for(int i=n+4; i>4; i--) {
                a[i][j]+=max(max(a[i+1][j+2], a[i+2][j+1]), max(a[i-1][j+2], a[i-2][j+1]));
            }
        }
        printf("%d\n", a[x][y]);
    }
    return 0;
}

thanks beforehand.

idea is, i used extra array indices instead of checking boundaries, also i calculated the max value among 4 available moves, when doing this i recursively(or iteratively, i dont know) loop from (supposed to be)leftmost array boundary, when reaching column of K(pos y here) stop loop.