算法题-分治法解决majority element

最新推荐文章于 2022-10-27 17:29:32 发布

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最新推荐文章于 2022-10-27 17:29:32 发布

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本文介绍了一个用于寻找数组中多数元素的递归算法实现。多数元素是指在数组中出现次数超过一半的元素。文章通过示例代码展示了如何使用递归方法找到多数元素，并详细解释了输入输出格式。

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题目：

Given an array of size n, find the majority element. The majority element is the element that appears more than b n 2 c times.You may assume that the array is non-empty and the majority element always exist in the array.

INPUT:

Line 1: the length of array.

Line 2: the all elements in array and split by spaces

OUTPUT:

Line 1: A single integer that is the majority element.

代码：

#include<iostream>
#include<vector>

using namespace std;

int findMajority(vector<int>& nums,int start,int end) {
	
	if (start >= end)return nums[end];
	int mid = start + (end - start) / 2;
	int m1 = findMajority(nums,start, mid);
	int m2 = findMajority(nums,mid + 1,end);

	int count = 0;
	for (int i = start; i <= end; i++) {
		if (nums[i] == m1)count++;
	}
	if (count > (end - start + 1) / 2)return m1;
	return m2;
}

int main() {
	int n;
	cin >> n;
	
	vector<int> nums;
	for (int i = 0; i < n; i++) {
		int t;
		cin >> t;
		nums.push_back(t);
	}

	int res = findMajority(nums, 0, n - 1);
	cout << res;

	int c;
	cin >> c;

	return 0;
}