Unique Paths II

arraydynamic programmingmatrix

Problem Statement

You are given an m x n integer array grid . There is a robot initially located at the top-left corner (i.e., grid[0][0] ). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1] ). The robot can only move either down or right at any point in time.

An obstacle and space are marked as 1 or 0 respectively in grid . A path that the robot takes cannot include any square that is an obstacle.

Return the number of possible unique paths that the robot can take to reach the bottom-right corner .

The testcases are generated so that the answer will be less than or equal to 2 * 10 ^9 .

Examples

Example 1

Input: obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]
Output: 2
There is one obstacle in the middle of the 3x3 grid above.
There are two ways to reach the bottom-right corner:
1. Right -> Right -> Down -> Down
2. Down -> Down -> Right -> Right

Example 2

Input: obstacleGrid = [[0,1],[0,0]]
Output: 1

Constraints

m == obstacleGrid.length

n == obstacleGrid[i].length

1 <= m, n <= 100

obstacleGrid[i][j] is 0 or 1 .

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicDynamic Programming