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Java Solution for LeetCode algorithm problems, continually updating
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package g0001_0100.s0052_n_queens_ii;
// #Hard #Backtracking #2022_06_17_Time_1_ms_(97.55%)_Space_41.4_MB_(37.24%)
public class Solution {
public int totalNQueens(int n) {
boolean[] row = new boolean[n];
boolean[] col = new boolean[n];
boolean[] diagonal = new boolean[n + n - 1];
boolean[] antiDiagonal = new boolean[n + n - 1];
return totalNQueens(n, 0, row, col, diagonal, antiDiagonal);
}
private int totalNQueens(
int n,
int r,
boolean[] row,
boolean[] col,
boolean[] diagonal,
boolean[] antiDiagonal) {
if (r == n) {
return 1;
}
int count = 0;
for (int c = 0; c < n; c++) {
if (!row[r] && !col[c] && !diagonal[r + c] && !antiDiagonal[r - c + n - 1]) {
row[r] = col[c] = diagonal[r + c] = antiDiagonal[r - c + n - 1] = true;
count += totalNQueens(n, r + 1, row, col, diagonal, antiDiagonal);
row[r] = col[c] = diagonal[r + c] = antiDiagonal[r - c + n - 1] = false;
}
}
return count;
}
}