N-Queens

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The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.

Given an integer n, return all distinct solutions to the n-queens puzzle.

Each solution contains a distinct board configuration of the n-queens‘ placement, where ‘Q‘ and ‘.‘ both indicate a queen and an empty space respectively.

For example,
There exist two distinct solutions to the 4-queens puzzle:

[
 [".Q..",  // Solution 1
  "...Q",
  "Q...",
  "..Q."],

 ["..Q.",  // Solution 2
  "Q...",
  "...Q",
  ".Q.."]
]

C++:

class Solution {
public:
    
    void print(int queue[], int n, vector<vector<string>> &qipan) {
        int i, j;
        /*for(i = 0; i < n; i++) {
            printf("row :%d, col :%d\n", i , queue[i]);
        } */ 
        vector<string> method;
        for(i = 0; i < n; i++) {
            string str(n,'.');
            str[queue[i]] = 'Q';  
            method.push_back(str);
        }
            //printf("\n");
        qipan.push_back(method);
        //printf("\n");
    }

    void testQueue(int queue[], int row, int n, vector<vector<string>> &qipan) {
        int j, k;
        if(row >= n) print(queue, n, qipan);
        else {
            for(j = 0; j < n; j++) {
                queue[row] = j;
                for(k = 0; k < row; k++) {
                    if((queue[k] - queue[row]) * (fabs(queue[k] - queue[row]) - fabs(k - row)) == 0) {
                        break; 
                    }
                    if(k == row - 1) testQueue(queue, row + 1, n, qipan);
                }
            }
        }
    }

    vector<vector<string>> solveNQueens(int n) {
        vector<vector<string>> qipan;
        int queue[n];
        int i;
        for(i = 0; i < n; i++ ) queue[i] = -1;
        for(i = 0; i < n; i++) {
            //printf("method :\n");
            queue[0] = i;
            testQueue(queue, 1, n, qipan);
        }
        return qipan;
    }
};

#include<stdio.h>
#include<math.h>

#define N 1

char qipan[100][N][N];
static int index = 0;

void print(int queue[], int n) {
    int i, j;
    for(i = 0; i < n; i++) {
        printf("row :%d, col :%d\n", i , queue[i]);
    }  
   
    for(i = 0; i < n; i++) {
        for(j = 0; j < n; j++) {
            if(queue[i] == j)
                qipan[index][i][j] = 'Q';
            else qipan[index][i][j] = '.';
            printf("%c ", qipan[index][i][j]);
        }
        printf("\n");
    }
    printf("\n");
}

void testQueue(int queue[], int row, int n) {
    int j, k;
    if(row >= n) print(queue, n);
    else {
        for(j = 0; j < n; j++) {
            queue[row] = j;
            for(k = 0; k < row; k++) {
                if((queue[k] - queue[row]) * (fabs(queue[k] - queue[row]) - fabs(k - row)) == 0) {
                    break; 
                }
                if(k == row - 1) testQueue(queue, row + 1, n);
            }
        }
    }
}

void solveNQueens(int n) {
    int queue[n];
    int i;
    for(i = 0; i < n; i++ ) queue[i] = -1;
    for(i = 0; i < n; i++) {
        printf("method :\n");
        queue[0] = i;
        testQueue(queue, 1, n);
    }
}

void main() {
    solveNQueens(N);
}

N-Queens

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原文地址：http://blog.csdn.net/uj_mosquito/article/details/42876523