使用Python写一个线段树模板

好的，这个问题属于计算机科学方面，我可以为你提供线段树模板的Python代码：

class SegmentTree():
    def __init__(self, nums):
        self.nums = nums
        self.tree = [0] * 4 * len(nums)
        self.build(1, 0, len(nums)-1)

    def build(self, node, start, end):
        if start == end:
            self.tree[node] = self.nums[start]
        else:
            mid = (start + end) // 2
            self.build(2*node, start, mid)
            self.build(2*node+1, mid+1, end)
            self.tree[node] = self.tree[2*node] + self.tree[2*node+1]

    def update(self, node, start, end, idx, val):
        if start == end:
            self.nums[idx] = val
            self.tree[node] = val
        else:
            mid = (start + end) // 2
            if idx >= start and idx <= mid:
                self.update(2*node, start, mid, idx, val)
            else:
                self.update(2*node+1, mid+1, end, idx, val)
            self.tree[node] = self.tree[2*node] + self.tree[2*node+1]

    def query(self, node, start, end, left, right):
        if start > right or end < left:
            return 0
        if start >= left and end <= right:
            return self.tree[node]
        mid = (start + end) // 2
        return self.query(2*node, start, mid, left, right) + self.query(2*node+1, mid+1, end, left, right)

这是一个基本的线段树模板，包含了建树、更新和查询操作。您可以根据需要进行修改和扩展。