my code 20101220_2

Just for learning...

 

 

#include <stdlib.h>
#include <stdio.h>

#define SIZE 8

void printqueen(int arr[][SIZE]);
int queen(int x, int y);
int lost(int x, int y);

static int arr[8][8] = {
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0},
                    {0,0,0,0,0,0,0,0}
                    };

int main(void){
    printqueen(arr);
    lost(0,0);
    printqueen(arr);
    return 0;
}

void printqueen(int arr[][SIZE]){
    int a, b;
    for(a = 0;a < SIZE;a++)
    {
        for(b = 0; b < SIZE; b++)
        {
            if(arr[a][b] != 0)
                printf("* ");
            else
                printf(". ");
        }
        putchar('\n');
    }
    puts("-----------------\n");
}

//if can be falldown, return 1, else return 0

int queen(int x, int y){
    int i, j;
    for(i = 0; i < SIZE; i++)
    {
        if(i == x) continue;
        if(arr[i][y] == 1) return 0;
    }

    for(j = 0; j < SIZE; j++)
    {
        if(j == y) continue;
        if(arr[x][j] == 1) return 0;
    }

    for(i = 0; i < SIZE; i++)
        for(j = 0; j < SIZE; j++)
        {
            if(i == x && j == y) continue;
            if( ((x + y) == (i + j)) || ((y - x) == (j - i)) ){
                if(arr[i][j] == 1) return 0;
            }
        }
    return 1;
}

int lost(int x, int y){
    int xx, yy;
    //printf("--%d--%d--\n", x, y);

    if(y > SIZE) return 0;
    for(xx = x; xx < SIZE; xx++)
    {
        yy = y;
        if(queen(xx, yy))
        {
            arr[xx][yy] = 1;
            if(lost(++xx, 0))
                arr[xx][yy] = 1;
            else
                lost(xx, ++yy);

            return 1;
        }
        return 0;
    }
    return 0;
}