Problem
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.
Example 1:
Input: [3,2,3]
Output: 3
Example 2:
Input: [2,2,1,1,1,2,2]
Output: 2
Solution 1
/**
* @param {number[]} nums
* @return {number}
*/
var majorityElement = function(nums) {
var map = {};
var max = 0;
var majorNum = 0;
var len = nums.length;
for (var i = 0; i < len; i++) {
if (!map[nums[i]]) map[nums[i]] = 0;
map[nums[i]]++;
if (map[nums[i]] > max) {
majorNum = nums[i];
max = map[nums[i]];
}
}
return majorNum;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).
Solution 2
/**
* @param {number[]} nums
* @return {number}
*/
var majorityElement = function(nums) {
var count = 0;
var majorNum = 0;
var len = nums.length;
for (var i = 0; i < len; i++) {
if (!count) {
majorNum = nums[i];
count = 1;
} else {
count += (nums[i] === majorNum ? 1 : -1);
}
}
return majorNum;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(1).