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119. Pascals Triangle II

Array Dynamic Programming

Problem - Pascals Triangle II

Easy

Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal's triangle.

In Pascal's triangle, each number is the sum of the two numbers directly above it as shown:

 

Example 1:

Input: rowIndex = 3
Output: [1,3,3,1]

Example 2:

Input: rowIndex = 0
Output: [1]

Example 3:

Input: rowIndex = 1
Output: [1,1]

 

Constraints:

  • 0 <= rowIndex <= 33

 

Follow up: Could you optimize your algorithm to use only O(rowIndex) extra space?

Solutions

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class Solution:
    def getRow(self, rowIndex: int) -> List[int]:
        dp = [1] * (rowIndex + 1)
        for i in range(2, rowIndex + 1):
            for j in range(i - 1, 0, -1):
                dp[j] += dp[j - 1]

        return dp

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 17.7 MB (81.68%)