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‎Challenges/2021/April-LeetCoding-Challenge.md

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|48.|[Rotate Image](https://leetcode.com/problems/rotate-image/)|[Python](/Medium/48.RotateImage.py)|Medium|
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|1642.|[Furthest Building You Can Reach](https://leetcode.com/problems/furthest-building-you-can-reach/)|~~Python~~|Medium|
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|326.|[Power of Three](https://leetcode.com/problems/power-of-three/)|[Python](/Easy/326.PowerofThree.py)|Easy|
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|63.|[Unique Paths II](https://leetcode.com/problems/unique-paths-ii/)|[Python](/Medium/63.UniquePathsII.py)|Medium|
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## License
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The code is open-source and licensed under the [MIT License](/LICENSE).

‎Medium/63.UniquePathsII.py

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'''
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A robot is located at the top-left corner of a m x n grid
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(marked 'Start' in the diagram below).
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The robot can only move either down or right at any point
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in time. The robot is trying to reach the bottom-right
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corner of the grid (marked 'Finish' in the diagram below).
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Now consider if some obstacles are added to the grids.
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How many unique paths would there be?
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An obstacle and space is marked as 1 and 0 respectively
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in the grid.
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Example:
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Input: obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]
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Output: 2
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Explanation: There is one obstacle in the middle of the
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3x3 grid above.
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There are two ways to reach the bottom-right
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corner:
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1. Right -> Right -> Down -> Down
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2. Down -> Down -> Right -> Right
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Example:
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Input: obstacleGrid = [[0,1],[0,0]]
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Output: 1
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Constraints:
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- m == obstacleGrid.length
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- n == obstacleGrid[i].length
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- 1 <= m, n <= 100
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- obstacleGrid[i][j] is 0 or 1.
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'''
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#Difficulty: Medium
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#41 / 41 test cases passed.
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#Runtime: 40 ms
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#Memory Usage: 14.1 MB
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#Runtime: 40 ms, faster than 78.35% of Python3 online submissions for Unique Paths II.
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#Memory Usage: 14.1 MB, less than 94.59% of Python3 online submissions for Unique Paths II.
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class Solution:
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def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:
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# count paths in the first row
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for j in range(len(obstacleGrid[0])):
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if obstacleGrid[0][j] != 1:
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if j == 0:
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obstacleGrid[0][j] = 1
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else:
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obstacleGrid[0][j] += obstacleGrid[0][j-1]
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else:
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obstacleGrid[0][j] = 0
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# count paths in the rest of the matrix
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for i in range(1, len(obstacleGrid)):
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for j in range(len(obstacleGrid[0])):
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if obstacleGrid[i][j] != 1:
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if j != 0:
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obstacleGrid[i][j] += (obstacleGrid[i][j-1] + obstacleGrid[i-1][j])
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else:
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obstacleGrid[i][j] += obstacleGrid[i-1][j]
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else:
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obstacleGrid[i][j] = 0
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return obstacleGrid[-1][-1]

‎README.md

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# Python solutions of LeetCode problems.
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![Language](https://img.shields.io/badge/language-Python-blue.svg)&nbsp;
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![Problems Solved](https://img.shields.io/badge/problems%20solved-548%2F1665-orange)&nbsp;
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![Problems Solved](https://img.shields.io/badge/problems%20solved-549%2F1665-orange)&nbsp;
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[![License](https://img.shields.io/badge/license-MIT-green.svg)](./LICENSE)&nbsp;
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![Update](https://img.shields.io/badge/update-Daily-brightgreen.svg)&nbsp;
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<br><br>
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- [January LeetCoding Challenge](/Challenges/2021/January-LeetCoding-Challenge.md) - 27/31
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- [February LeetCoding Challenge](/Challenges/2021/February-LeetCoding-Challenge.md) - 23/28
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- [March LeetCoding Challenge](/Challenges/2021/March-LeetCoding-Challenge.md) - 23/31
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- [April LeetCoding Challenge](/Challenges/2021/April-LeetCoding-Challenge.md) - 20/30
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- [April LeetCoding Challenge](/Challenges/2021/April-LeetCoding-Challenge.md) - 21/30
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<br><br>
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## Solutions
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*P.S. If you like this, please leave me a star.* ★
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|58.|[Length of Last Word](https://leetcode.com/problems/length-of-last-word/)|[Python](/Easy/58.LengthofLastWord(string).py)|Easy|`String`|
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|59.|[Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii/)|[Python](/Medium/59.SpiralMatrixII.py)|Medium|spaghetti|
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|61.|[Rotate List](https://leetcode.com/problems/rotate-list/)|[Python](/Medium/61.RotateList.py)|Medium|`Linked List`|
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|63.|[Unique Paths II](https://leetcode.com/problems/unique-paths-ii/)|[Python](/Medium/63.UniquePathsII.py)|Medium|`DP`|
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|64.|[Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/MinimumPathSum.py)|Medium|
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|66.|[Plus One](https://leetcode.com/problems/plus-one/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/66.PlusOne.py)|Easy||
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|67.|[Add Binary](https://leetcode.com/problems/add-binary/)|[Python](/Easy/67.AddBinary.py)|Easy||

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