89 lines
1.9 KiB
C++
89 lines
1.9 KiB
C++
/*
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* C++ Program to Solve N-Queen Problem
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*/
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#include <iostream>
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#include <cstdio>
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#include <cstdlib>
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#define N 8
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using namespace std;
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/* print solution */
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void printSolution(int board[N][N])
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{
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for (int i = 0; i < N; i++)
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{
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for (int j = 0; j < N; j++)
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cout<<board[i][j]<<" ";
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cout<<endl;
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}
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}
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/* check if a queen can be placed on board[row][col]*/
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bool isSafe(int board[N][N], int row, int col)
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{
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int i, j;
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for (i = 0; i < col; i++)
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{
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if (board[row][i])
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return false;
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}
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for (i = row, j = col; i >= 0 && j >= 0; i--, j--)
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{
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if (board[i][j])
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return false;
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}
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for (i = row, j = col; j >= 0 && i < N; i++, j--)
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{
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if (board[i][j])
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return false;
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}
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return true;
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}
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/*solve N Queen problem */
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bool solveNQUtil(int board[N][N], int col)
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{
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if (col >= N)
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return true;
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for (int i = 0; i < N; i++)
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{
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if ( isSafe(board, i, col) )
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{
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board[i][col] = 1;
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if (solveNQUtil(board, col + 1) == true)
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return true;
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board[i][col] = 0;
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}
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}
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return false;
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}
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/* solves the N Queen problem using Backtracking.*/
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bool solveNQ()
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{
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int board[N][N] = {0};
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if (solveNQUtil(board, 0) == false)
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{
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cout<<"Solution does not exist"<<endl;
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return false;
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}
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printSolution(board);
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return true;
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}
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// Main
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int main()
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{
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solveNQ();
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return 0;
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}
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/*
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1 0 0 0 0 0 0 0
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0 0 0 0 0 0 1 0
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0 0 0 0 1 0 0 0
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0 0 0 0 0 0 0 1
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0 1 0 0 0 0 0 0
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0 0 0 1 0 0 0 0
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0 0 0 0 0 1 0 0
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0 0 1 0 0 0 0 0
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