叠框

#include <stdio.h>
#include <stdbool.h>

int main() {
    int n;
    char inner,outer;
    bool flag=true;
    while(scanf("%d %c %c",&n,&inner,&outer) != EOF){
        if(flag == true){
            flag = false;
        }else{
            printf("\n");
        }
        char matrix[80][80]={0};
        int length = 1;
        int x,y;
        char curChar = inner;
        for(length=1,x=n/2,y=n/2;length<=n;length=length+2,--x,--y){
            for(int i=x,j=y;i<x+length;++i){
                matrix[i][j] = curChar ;
            }
            for(int i=x,j=y;j<y+length;++j){
                matrix[i][j]=curChar;
            }
            for(int i=x+length-1,j=y;j<y+length;++j){
                matrix[i][j]=curChar;
            }
            for(int i = x,j=y+length-1;i<x+length;++i){
                matrix[i][j]=curChar;
            }
            if(curChar == inner){
                curChar=outer;
            } else{
                curChar=inner;
            }
        }
        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){
            printf("%s\n",matrix[i]);
        }

    }
}