八皇后问题

来源：互联网发布：windows图形编程 pdf 编辑：程序博客网时间：2024/05/17 04:28
#include <stdio.h>#include <stdlib.h>#include <string.h>typedef int bool;#define true 1#define false 0#define M (8)#define OK(x, y) ((x) >= 0 && (x) < M && (y) >= 0 && (y) < M)static int board[M][M]; /* 棋盘 */int cnt = 0; /* 记录解法种类 *//*判断当前位置是否合法？如果横竖斜方向存在皇后，则返回0，否则返回1*/static int right_pos(int row, int col){int i = 0;for(i = 0; i < M; i++){if(board[row][i] || board[i][col])return false;if(OK(row - i, col - i)){if(board[row - i][col - i])return false;}if(OK(row + i, col + i)){if(board[row + i][col + i])return false;}if(OK(row + i, col - i)){if(board[row + i][col - i])return false;}if(OK(row - i, col + i)){if(board[row - i][col + i])return false;}}return true;}/*自动根据棋盘状态判断下一步应该走向哪里*/static bool next(int * row, int * col){int i;/*  换行 */if(*row + 1 < M){*row += 1;return true;}else{/* 否则，改变列，回溯 *//* 如果回溯到第0行还不行，返回false */if(*col == 0)return false;(*col)--;/* 找到上一列的位置 */for(i = 0; i < M; i++)if(board[i][*col])break;/* 清除不合法的位置 */board[i][*col] = 0;*row = i;return next(row, col);}}void print(){int i, j;cnt++;printf("第%d种解法:\n", cnt);/* 打印结果 */for(i = 0; i < M; i++){for(j = 0; j < M; j++){if(board[i][j])printf("Q ");elseprintf("* ");}printf("\n");}printf("\n");getchar();}void go(){int row, col, good;row = col = 0;good = 1;do{if(good){board[row][col] = 1;if(col == M - 1){print();board[row][col] = 0;row = M - 1;if(!next(&row, &col))return ;}else{col += 1;row = 0;}}elseif(!next(&row, &col))return ;good = right_pos(row, col);}while(1);}int main(){go();printf("COUNT:%d\n", cnt);return 0;}
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