P12 叠框

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

char matrix[80][80];

int main(){

    int n;
    char a,b;

    bool firsrcase = true;
    //scanf("%d%c%c", &n, &a, &b) != EOF  cin >> n >> a >> b
    while(scanf("%d %c %c", &n, &a, &b)!= EOF){
        if(firsrcase == true){
            firsrcase = false;
        }else{
            printf("\n");
        }      
        for(int i = 0; i <= n/2; ++i){
            int j = n-1-i;
            int length = n- 2 * i; //当前圈的边长
            char c;
            if(( n/2 -i) % 2 == 0){
                c=a;
            }else{
                c=b;
            }
            for(int k = 0; k < length; ++k){
                matrix[i][i+k] = c;
                matrix[i+k][i] = c;
                matrix[j][j-k] = c;
                matrix[j-k][j] = c;
            }
        }

        if(n!=1){
            matrix[0][0] = ' ';
            matrix[0][n-1] = ' ';
            matrix[n-1][0] = ' ';
            matrix[n-1][n-1] = ' ';
        }
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < n; ++j){
                printf("%c",matrix[i][j]);
            }
            printf("\n");
        }
    }
    return 0;

}