n皇后问题—回溯法 C++实现

#include <iostream>#include <vector>using namespace std;bool isLegal(int row,int col,vector<string> &v,int n){for(int i=0;i<row;++i)if(v[i][col]=='Q') return false;for(int i=row-1,j=col-1;i>=0&&j>=0;--i,--j)if(v[i][j]=='Q') return false;for(int i=row-1,j=col+1;i>=0&&j<n;--i,++j)if(v[i][j]=='Q') return false;return true;}void snqHelp(vector<vector<string>> &res,vector<string> &v,int row,int n){if(row==n){res.push_back(v);return;}for(int col=0;col<n;++col){if(isLegal(row,col,v,n)){v[row][col]='Q';snqHelp(res,v,row+1,n);v[row][col]='.';}}}vector<vector<string>> solveNQueens(int n){vector<vector<string>> res;vector<string> v(n,string(n,'.'));snqHelp(res,v,0,n);return res;}int main(int argc, char const *argv[]){int n;cout<<"input n :";cin>>n;vector<vector<string>> res=solveNQueens(n);for(auto vstr:res){for(auto x:vstr)cout<<x<<endl;string line(2*n,'-');cout<<line<<endl;}cout<<"Total solution :"<<res.size()<<endl;return 0;}