# Java backtracking solution, based on previous "N-Queens" problem

• ``````public class Solution {

char[][] board;
int n;
int totalCnt;

public int totalNQueens(int n) {

board = new char[n][n];
this.n = n;

for (int i=0; i<n; i++)
for (int j=0; j<n; j++)
board[i][j] = '.';

totalCnt = 0;

dfs(n, 0, path);

}

void dfs(int n, int start, List<String> path) {
if (path.size() == n) {
totalCnt++;
return;
}

for (int i=0; i<n; i++) {
if (!isValid(start, i)) {
continue;
}
board[start][i] = 'Q';
String str=new String(board[start]);
dfs(n, start+1, path);
path.remove(path.size()-1);
board[start][i] = '.';
}
}

boolean isValid(int row, int col) {
for (int i=0; i<n; i++) {
if (board[i][col] == 'Q')
return false;
}

for (int i=0; i<n; i++) {
if (board[row][i] == 'Q')
return false;
}

for (int i=row, j=col; i>=0 && j>=0; i--, j--) {
if (board[i][j] == 'Q')
return false;
}

for (int i=row, j=col; i<n && j<n; i++, j++) {
if (board[i][j] == 'Q')
return false;
}

for (int i=row, j=col; i<n && j>=0; i++, j--) {
if (board[i][j] == 'Q')
return false;
}

for (int i=row, j=col; i>=0 && j<n; i--, j++) {
if (board[i][j] == 'Q')
return false;
}

return true;
}
}
``````

Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.