算法面试题-leetcode学习之旅（一）

问题描述

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.

解决思路：

推荐算法：

Moore voting algorithm–每找出两个不同的element，就成对删除即count–，最终剩下的一定就是所求的。时间复杂度：O(n)

java实现：

public class Solution {
public int majorityElement(int[] nums) {
//0627
//Moore Voting
int n = nums.length;

int candidate = 0;
int times = 0;
for(int i = 0; i < n; i++){
if(times == 0) candidate = nums[i];
if(nums[i] != candidate){
times--;
} else{
times++;
}
}
return candidate;
//0631
}
}

c实现：

class Solution {
public:
int majorityElement(vector<int> &num) {

int elem = 0;
int count = 0;

for(int i = 0; i < num.size(); i++)  {

if(count == 0)  {
elem = num[i];
count = 1;
}
else    {
if(elem == num[i])
count++;
else
count--;
}

}
return elem;
}
　　};