169. Majority Element

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.

 

找到一堆数中出现次数>n/2 的那个数。

普通解法。可能用map 或者二分，但是仔细想一想可以用o（n）的解法。

其实就是求这堆数的众数。

class Solution {
public:
    int majorityElement(vector<int>& nums) {
        int n = nums.size();
        int can = nums[0];
        int cnt = 1;
        for (int i = 1; i < n; ++i) {
            if (nums[i] == can) cnt++;
            else {
                cnt--;
                if (cnt == 0) can = nums[i],cnt = 1;
            }
        }
        return can;
    }
};

 

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