回溯法-n皇后

#include<iostream>using namespace std;int legal(int i,int j,int a[][4]){int cn = 0;for(int row = 0;row<=i;row++){if(a[row][j]!=0)cn++;}if(cn>=2){return 0;}return 1;}int Trial(int i,int n,int a[][4]){if(i>=n){for(int row = 0;row<n;row++){for(int col = 0;col<n;col++)if(a[row][col]!=0)cout<<col;}cout<<endl;return 1;}elsefor(int j = 0;j<n;j++){a[i][j] = 1;if(legal(i,j,a)){Trial(i+1,n,a);}a[i][j] = 0;//回溯重要的标志}}int main(void){int a[4][4]={0};for(int row = 0;row<4;row++){for(int col = 0;col<4;col++)cout<<a[row][col];cout<<endl;}Trial(0,4,a);return 0;}