题解 | #N皇后问题#

//定义一个数组，每个数组的值代表皇后的位置，没放一步都判断当前位置是否有效，有效则继续下一步，知道n 步都正确，次数加1 ，遍历得到所有的次数
import java.util.*;


public class Solution {
/**
 *
 * @param n int整型 the n
 * @return int整型
 */
public int Nqueen (int n) {

    int[] queen = new int[n];
    int res = 0;
    res = getQueen(queen, 1, n, res);
    return  res;
    // write code here
}

public int getQueen(int[] queen, int steep, int n, int res) {

    for (int i = 1; i <= n; i++) {
        queen[steep - 1] = i;
        if (curSteep(queen, steep)) {
            if (steep == n) {
                res++;
            } else {
                res = getQueen(queen,  steep + 1, n, res);
            }
        }
    }
    return res;
}
public boolean  curSteep(int[] queen, int steep) {
    for (int j = 0; j < steep - 1; j++) {
        if (queen[j] == queen[steep - 1] ||
                Math.abs(queen[steep - 1] - queen[j]) == steep - j - 1) {
            return false;
        }
    }
    return true;
}

}