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

solutions/0/q63/solution.go

@@ -0,0 +1,28 @@
+package q63
+
+func uniquePathsWithObstacles(obstacleGrid [][]int) int {
+	w, h := len(obstacleGrid[0]), len(obstacleGrid)
+	if obstacleGrid[h-1][w-1]+obstacleGrid[0][0] > 0 {
+		return 0
+	}
+
+	obstacleGrid[h-1][w-1] = -1
+	for i := w + h - 2; i >= 0; i-- {
+		for x := min(i, w-1); x >= 0 && i-x < h; x-- {
+			y := i - x
+			if obstacleGrid[y][x] == 1 {
+				continue
+			}
+			if x+1 < w && obstacleGrid[y][x+1] != 1 {
+				obstacleGrid[y][x] += obstacleGrid[y][x+1]
+			}
+			if y+1 < h && obstacleGrid[y+1][x] != 1 {
+				obstacleGrid[y][x] += obstacleGrid[y+1][x]
+			}
+		}
+	}
+
+	return -1 * obstacleGrid[0][0]
+}
+
+var _ = uniquePathsWithObstacles