[勇者闯LeetCode] 169. Majority Element

[勇者闯LeetCode] 169. Majority Element

Description

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.

You may assume that the array is non-empty and the majority element always exist in the array.

Information

• Tags: Array | Divide and Conquer | Bit Manipulation
• Difficulty: Easy

Solution

利用位操作，先初始化输出元素为首元素，其出现次数cnt为1，扫描数组，若当前元素与输出元素相同，则cnt加1；否则cnt减1，且cnt为0时，将输出元素重置为当前元素，出现次数cnt重置为1，扫描结束后输出元素将是数组中出现次数超过一半的那个元素。

C++ Code

class Solution {public:    int majorityElement(vector<int>& nums) {        int ans = nums[0], cnt = 1;        for (const auto& num : nums) {            if (num == ans) {                ++cnt;            }            else {                --cnt;                if (cnt == 0) {                    ans = num;                    cnt = 1;                }            }        }        return ans;    }};