N queen question, n queen

N queen question, n queen
Description

Place n queens that are not under attack on the chessboard of n × n grids. According to the rules of chess, the queen can attack pawns in the same row, column, or diagonal line. The problem after n is equivalent to placing n on the n × n board. Any two queens may wish to be on the same row, column, or diagonal line.

Input/Output Format

Input description:

Given the size of the Board n (n ≤ 13)

Output description:

The output integer indicates the number of placement methods.

Input and Output sample

Input example #1:

8

Output sample #1:

92

Ideas

Search.

Code # include <stdio. h> int a [200] = {0}, B [200] = {0}, c [200] = {0}, d [200], p = 0; int search (int n, int s) {int I; for (I = 1; I <= n; I ++) {if (a [I] = 0 & B [I + s] = 0 & c [s-I + n-1] = 0) {a [I] = 1; B [I + s] = 1; c [s-I + n-1] = 1; d [s] = I; if (s = n) p ++; else search (n, s + 1); a [I] = 0; B [I + s] = 0; c [s-I + n-1] = 0 ;}} int main () {int n; scanf ("% d", & n); search (n, 1 ); if (p = 0) printf ("no solute! "); Else printf (" % d ", p); return 0;} View Code