add new solutions

solutions/0/q52/solution.go

@@ -0,0 +1,24 @@
+package q52
+
+func findNSolutions(nQueen, row int, rows, cols, diag1, diag2 []bool) int {
+	solutions := 0
+	if row == nQueen {
+		return 1
+	}
+	for col := range nQueen {
+		// if grid[row][col] is placeable
+		if !rows[row] && !cols[col] && !diag1[row+col] && !diag2[row-col+nQueen] {
+			rows[row], cols[col], diag1[row+col], diag2[row-col+nQueen] = true, true, true, true
+			solutions += findNSolutions(nQueen, row+1, rows, cols, diag1, diag2)
+			rows[row], cols[col], diag1[row+col], diag2[row-col+nQueen] = false, false, false, false
+		}
+	}
+	return solutions
+}
+
+func totalNQueens(n int) int {
+	buf := make([]bool, 6*n)
+	return findNSolutions(n, 0, buf[0:n], buf[n:2*n], buf[2*n:4*n], buf[4*n:])
+}
+
+var _ = totalNQueens