LeetCode题解(1157)：子数组中占绝大多数的元素(Python)

题目：​​原题链接​​（困难）

标签：二分查找、线段树、设计

解法一：

import bisect
import collections
from typing import List


class MajorityChecker:

    def __init__(self, arr: List[int]):
        self.high = len(arr).bit_length()
        self.size = 2 ** self.high - 1

        # 构造线段树
        self.tree = [(0, 0)] * (2 * self.size + 1)

        # 计算叶结点
        for i in range(len(arr)):
            self.tree[self.size + i] = (arr[i], 1)

        # 计算中间节点
        for i in range(self.high - 1, -1, -1):
            for j in range(2 ** i - 1, 2 ** (i + 1) - 1):
                left_val, left_count = self.tree[j * 2 + 1]
                right_val, right_count = self.tree[j * 2 + 2]
                self.tree[j] = self.merge(left_val, left_count, right_val, right_count)

        # 统计每一个的数的坐标列表
        self.idx = collections.defaultdict(list)
        for i, num in enumerate(arr):
            self.idx[num].append(i)

    def query(self, left: int, right: int, threshold: int) -> int:
        # ---------- 摩尔投票法寻找需要查询的数字 ----------
        l = left + self.size
        r = right + self.size

        val, count = 0, 0

        # print(left, right)
        while l <= r:
            if not l & 1:  # 左侧为右结点
                val, count = self.merge(val, count, self.tree[l][0], self.tree[l][1])
                # print("添加:", left, self.tree[left])
                l //= 2
            else:
                l //= 2

            if r & 1:  # 右侧为左节点
                val, count = self.merge(val, count, self.tree[r][0], self.tree[r][1])
                # print("添加:", right, self.tree[right])
                r = r // 2 - 1
            else:
                r = r // 2 - 1
            # print(left, right)

        l_idx = bisect.bisect_left(self.idx[val], left)
        r_idx = bisect.bisect_right(self.idx[val], right)

        # print("最多值:", val, "超过其他的数量:", count, "->", "查询值:", [left, right], self.idx[val], "->", l_idx, r_idx)

        if r_idx - l_idx >= threshold:
            return val
        else:
            return -1

    @staticmethod
    def merge(v1, c1, v2, c2):
        if v1 == v2:
            return v1, c1 + c2
        else:
            if c1 < c2:
                v1, c1, v2, c2 = v2, c2, v1, c1
            return v1, c1 -