307. Range Sum Query – Mutable LeetCode Solution
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Table of Contents
- Problem Statement
- Complexity Analysis
- Range Sum Query – Mutable solution in C++
- Range Sum Query – Mutable solution in Java
- Range Sum Query – Mutable solution in Python
- Additional Resources
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Problem Statement of Range Sum Query – Mutable
Given an integer array nums, handle multiple queries of the following types:
Update the value of an element in nums.
Calculate the sum of the elements of nums between indices left and right inclusive where left <= right.
Implement the NumArray class:
NumArray(int[] nums) Initializes the object with the integer array nums.
void update(int index, int val) Updates the value of nums[index] to be val.
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]).
Example 1:
Input
[“NumArray”, “sumRange”, “update”, “sumRange”]
[[[1, 3, 5]], [0, 2], [1, 2], [0, 2]]
Output
[null, 9, null, 8]
Explanation
NumArray numArray = new NumArray([1, 3, 5]);
numArray.sumRange(0, 2); // return 1 + 3 + 5 = 9
numArray.update(1, 2); // nums = [1, 2, 5]
numArray.sumRange(0, 2); // return 1 + 2 + 5 = 8
Constraints:
1 <= nums.length <= 3 * 104
-100 <= nums[i] <= 100
0 <= index < nums.length
-100 <= val <= 100
0 <= left <= right < nums.length
At most 3 * 104 calls will be made to update and sumRange.
Complexity Analysis
- Time Complexity: O(\log n)
- Space Complexity: O(n)
307. Range Sum Query – Mutable LeetCode Solution in C++
class FenwickTree {
public:
FenwickTree(int n) : sums(n + 1) {}
void add(int i, int delta) {
while (i < sums.size()) {
sums[i] += delta;
i += lowbit(i);
}
}
int get(int i) const {
int sum = 0;
while (i > 0) {
sum += sums[i];
i -= lowbit(i);
}
return sum;
}
private:
vector<int> sums;
static inline int lowbit(int i) {
return i & -i;
}
};
class NumArray {
public:
NumArray(vector<int>& nums) : nums(nums), tree(nums.size()) {
for (int i = 0; i < nums.size(); ++i)
tree.add(i + 1, nums[i]);
}
void update(int index, int val) {
tree.add(index + 1, val - nums[index]);
nums[index] = val;
}
int sumRange(int left, int right) {
return tree.get(right + 1) - tree.get(left);
}
private:
vector<int> nums;
FenwickTree tree;
};
/* code provided by PROGIEZ */
307. Range Sum Query – Mutable LeetCode Solution in Java
class FenwickTree {
public FenwickTree(int n) {
sums = new int[n + 1];
}
public void add(int i, int delta) {
while (i < sums.length) {
sums[i] += delta;
i += lowbit(i);
}
}
public int get(int i) {
int sum = 0;
while (i > 0) {
sum += sums[i];
i -= lowbit(i);
}
return sum;
}
private int[] sums;
private static int lowbit(int i) {
return i & -i;
}
}
class NumArray {
public NumArray(int[] nums) {
this.nums = nums;
tree = new FenwickTree(nums.length);
for (int i = 0; i < nums.length; ++i)
tree.add(i + 1, nums[i]);
}
public void update(int index, int val) {
tree.add(index + 1, val - nums[index]);
nums[index] = val;
}
public int sumRange(int left, int right) {
return tree.get(right + 1) - tree.get(left);
}
private int[] nums;
private FenwickTree tree;
}
// code provided by PROGIEZ
307. Range Sum Query – Mutable LeetCode Solution in Python
class FenwickTree:
def __init__(self, n: int):
self.sums = [0] * (n + 1)
def add(self, i: int, delta: int) -> None:
while i < len(self.sums):
self.sums[i] += delta
i += FenwickTree.lowbit(i)
def get(self, i: int) -> int:
summ = 0
while i > 0:
summ += self.sums[i]
i -= FenwickTree.lowbit(i)
return summ
@staticmethod
def lowbit(i: int) -> int:
return i & -i
class NumArray:
def __init__(self, nums: list[int]):
self.nums = nums
self.tree = FenwickTree(len(nums))
for i, num in enumerate(nums):
self.tree.add(i + 1, num)
def update(self, index: int, val: int) -> None:
self.tree.add(index + 1, val - self.nums[index])
self.nums[index] = val
def sumRange(self, left: int, right: int) -> int:
return self.tree.get(right + 1) - self.tree.get(left)
# code by PROGIEZ
Additional Resources
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