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Copy pathN-Queen_Problem.cpp
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94 lines (88 loc) · 1.66 KB
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//C++ code
#include <iostream>
using namespace std;
bool isSafe(int board[][10],int i,int j,int n){
//check for column
for(int row=0;row<i;row++){
if(board[row][j]==1){
return false;
}
}
//check for left diagonal
int x=i;
int y=j;
while(x>=0 && y>=0){
if(board[x][y]==1){
return false;
}
x--;
y--;
}
//check for right diagonal
x=i;
y=j;
while(x>=0 && y<n){
if(board[x][y]==1){
return false;
}
x--;
y++;
}
return true;
}
bool solveNQueen(int board[][10],int i,int n){
//Base Case
if(i==n){
int count=0;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
if(board[i][j]==1){
count++;
}
}
}
if(count!=0){
cout<<"[";
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
if(board[i][j]==1){
cout<<j+1<<" ";
}
}
}
cout<<"] ";
}
else{
cout<<-1;
}
}
//rec case
for(int j=0;j<n;j++){
if(isSafe(board,i,j,n)){
board[i][j]=1;
bool nextQueenRakhPaye = solveNQueen(board,i+1,n);
if(nextQueenRakhPaye){
return true;
}
board[i][j]=0;
}
}
return false;
}
int main() {
int t;
cin>>t;
while(t--){
int n;
cin>>n;
if(n==2||n==3){
cout<<-1;
}
else{
int board[10][10]={0};
solveNQueen(board,0,n);
}
cout<<endl;
}
return 0;
}