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54 lines
1.3 KiB
Python
54 lines
1.3 KiB
Python
"""
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62. Unique Paths
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Difficulty: Medium
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https://leetcode.com/problems/unique-paths/
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──────────────────────────────────────────────────
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There is a robot on an m x n grid. The robot is initially located at
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the top-left corner (i.e., grid[0][0]). The robot tries to move to the
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bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only
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move either down or right at any point in time.
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Given the two integers m and n, return the number of possible unique
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paths that the robot can take to reach the bottom-right corner.
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The test cases are generated so that the answer will be less than or
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equal to 2 * 10^9.
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Example 1:
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Input: m = 3, n = 7
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Output: 28
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Example 2:
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Input: m = 3, n = 2
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Output: 3
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Explanation: From the top-left corner, there are a total of 3 ways to
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reach the bottom-right corner:
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1. Right -> Down -> Down
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2. Down -> Down -> Right
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3. Down -> Right -> Down
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Constraints:
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• 1 <= m, n <= 100
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"""
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class Solution:
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def uniquePaths(self, m: int, n: int) -> int:
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row = [1] * n
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for i in range(m - 1):
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newRow = [1] * n
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for j in range(n - 2, -1, -1):
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newRow[j] = newRow[j + 1] + row[j]
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row = newRow
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return row[0]
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