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Commit e5e12e3

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Range Sum Query - Immutable
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'''Leetcode- https://leetcode.com/problems/range-sum-query-immutable/ '''
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'''
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Given an integer array nums, handle multiple queries of the following type:
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Calculate the sum of the elements of nums between indices left and right inclusive where left <= right.
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Implement the NumArray class:
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NumArray(int[] nums) Initializes the object with the integer array nums.
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int sumRange(int left, int right) Returns the sum of the elements of nums between indices left and right inclusive (i.e. nums[left] + nums[left + 1] + ... + nums[right]).
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Example 1:
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Input
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["NumArray", "sumRange", "sumRange", "sumRange"]
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[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]
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Output
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[null, 1, -1, -3]
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Explanation
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NumArray numArray = new NumArray([-2, 0, 3, -5, 2, -1]);
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numArray.sumRange(0, 2); // return (-2) + 0 + 3 = 1
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numArray.sumRange(2, 5); // return 3 + (-5) + 2 + (-1) = -1
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numArray.sumRange(0, 5); // return (-2) + 0 + 3 + (-5) + 2 + (-1) = -3
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'''
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class NumArray:
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def __init__(self, nums):
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self.sums = nums[:]
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for i in range(1, len(self.sums)):
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self.sums[i] = self.sums[i-1] + nums[i]
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def sumRange(self, left: int, right: int):
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if left == 0:
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return self.sums[right]
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else:
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return self.sums[right] - self.sums[left-1]
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#T:O(n)
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#S:O(n)

‎README.md

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@@ -25,3 +25,5 @@ Check the notes for the explaination - [Notes](https://stingy-shallot-4ea.notion
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- [x] [Dynamic Programming](Dynamic-Programming)
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- [x] [Climbing Stairs](Dynamic-Programming/70-Climbing-Stairs.py)
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- [x] [Maximum Subarray](Dynamic-Programming/53-maximum-subarray.py)
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- [x] [Range Sum Query - Immutable](Dynamic-Programming/303-Range-Sum-Query-Immutable.py)
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