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