八皇后实现总结

问题描述

n*n的棋盘上放n个皇后

源码

#include<iostream>
using namespace std;
/*eight queens*/
int solutions = 0;
void printResults(int queens[], int n)
{
	int i, j;
	for (i = 0; i < n; i++)
	{
		for (j = 0; j < n; j++)
			cout << (j == queens[i] ? "1" : "o")<<" ";
		cout << endl;
	}
}
void tryRow(int queens[],int n,int row)  //前0~row-1行都放好的情况下，找第i行能放皇后的列
{
	int i,ok=1;
	for (int j = 0; j < n; j++)
	{
		ok = 1;    //don't forget this line!!!!
		//cout << row << endl;
		//判断是否此处是否与0~i-1行冲突，若冲突则直接进入下一个
		for (i = 0; i < row; i++)
			if ((queens[i] == j) || (i - row == queens[i] - j) || (i - row == j - queens[i]))
			{
				ok = 0;
				//cout << "row = " << row << "  j = " << j << "  not ok" << endl;
			}
		
		if (ok)
		{
			queens[row] = j;
			if (row == n-1) //have finished putting the last queen,print the result
			{//////////////////////right here bro!!!!!n-1 rather than n!!!
				solutions++;
				cout << endl << "----------------"<<endl ;
				printResults(queens, n);
			}
			else        //put the next queen
			{
				tryRow(queens, n, row + 1);
			}
		}
	}
}

int main()  //n*n的棋盘上摆n个皇后，任意两个不能同行同列或同斜线
{
	int n = 8;
	int *queens = new int[n];  //a的下标范围是0~n-1
	tryRow(queens, 8, 0);

	cout <<endl<< solutions;

	delete[] queens;
	while (1);
	return 0;
}

一些小坑

1. 忘了一处初始化：

for循环开始后，对每个j，先ok=1；

2 条件边界值写错，

应为 i == n -1 而不是i == n ,即行号范围是0~n-1，第n-1行填满即可输出