#!/usr/bin/env python3
"""307"""
from typing import List
class NumArray_Naive:
"""Naive implementation. Useless."""
def __init__(self, nums: List[int]):
self.nums = nums
def update(self, index: int, val: int) -> None:
"""Update."""
self.nums[index] = val
def sumRange(self, left: int, right: int) -> int:
"""sumRange."""
return sum(self.nums[left : right + 1])
class NumArray:
"""Segment Tree implementation."""
def __init__(self, nums: List[int]):
self.nums = nums
self.n = len(nums)
self.segment_tree = [0] * (len(nums) * 2)
self.build_segment_tree()
def build_segment_tree(self):
"""build segment tree."""
for i, j in zip(range(self.n, 2 * self.n), range(0, len(self.nums))):
self.segment_tree[i] = self.nums[j]
for i in reversed(range(1, self.n)):
self.segment_tree[i] = (
self.segment_tree[i * 2] + self.segment_tree[i * 2 + 1]
)
# print(self.segment_tree)
def update_segment_tree(self, index: int, val: int):
"""update segment tree."""
pos: int = index + self.n
self.segment_tree[pos] = val
while pos > 0:
left = pos
right = pos
if pos % 2 == 0:
right = pos + 1
else:
left = pos - 1
self.segment_tree[int(pos / 2)] = (
self.segment_tree[left] + self.segment_tree[right]
)
pos = int(pos / 2)
def update(self, index: int, val: int) -> None:
"""Update."""
self.update_segment_tree(index, val)
def sumRange(self, left: int, right: int) -> int:
"""sumRange."""
l = left + self.n
r = right + self.n
s: int = 0
while l <= r:
if (l % 2) == 1:
s += self.segment_tree[l]
l += 1
if (r % 2) == 0:
s += self.segment_tree[r]
r -= 1
l = int(l / 2)
r = int(r / 2)
return s
# Your NumArray object will be instantiated and called as such:
# obj = NumArray(nums)
# obj.update(index,val)
# param_2 = obj.sumRange(left,right)
def main():
"""Main."""
num_array = NumArray([1, 3, 5])
print(num_array.sumRange(0, 2))
num_array.update(1, 2)
print(num_array.sumRange(0, 2))
if __name__ == "__main__":
main()
