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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.
这道题有很多种解法,可以排序之后,直接返回中间值,时间复杂度为O(nlogn),可以hash之后找到数量最大的那个值,时间复杂度为O(n),但是需要额外的空间。我用的是计数法,具体看代码,时间复杂度为O(n),也不需要额外的空间。
1 class Solution { 2 public: 3 int majorityElement(vector<int> &num) { 4 int Number;int count=0; 5 if(num.empty()) 6 return 0; 7 for(auto v:num){ 8 if(count == 0) 9 Number = v; 10 if(Number == v) 11 count++; 12 else 13 count--; 14 } 15 return Number; 16 } 17 };
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原文地址:http://www.cnblogs.com/desp/p/4340363.html