Back to ChallengesUnique PathsMedium 25 min

Unique Paths

There is a robot on an m x n grid. The robot is initially at the top-left corner (0, 0) and wants to move to the bottom-right corner (m - 1, n - 1). The robot can only move down or right. Return the number of possible unique paths.

Examples

Input: m = 3, n = 7

Output: 28

Total paths is 28.

Constraints

• 1 <= m, n <= 100

Complexity Analysis

Time

O(m * n)

visiting each cell once.

Space

O(n)

only a single row tracker is needed.

Test Cases

#1 3x2 grid

Input: 3, 2

Expected: 3

#2 3x7 grid

Input: 3, 7

Expected: 28

#3 1x1 grid

Input: 1, 1

Expected: 1

JavaScript

Output

Click "Run Code" to see output here...