面試常考算法（六）——數組系列

1.求衆數

找到衆數，這個衆數出現的次數大於n/2

def majority_element(nums):
# moore投票法
    candidate = None
    count = 0
    for num in nums:
        if count == 0:
            candidate = num
        if num == candidate:
            count += 1
        else:
            count -= 1
    return candidate

2.有序數組的兩數和爲目標值

https://leetcode-cn.com/problems/two-sum-ii-input-array-is-sorted/

def two_sum(nums, tar):
	j = len(nums) - 1
	i = 0
	while i <j:
		sum_ = nums[i] + nums[j]
		if sum_ == tar:
			return [i+1,j+1]
		if sum_ > target:
			j-=1
		else:
			i+=1
	return None

3.數組的移動次數

https://leetcode-cn.com/problems/minimum-moves-to-equal-array-elements-ii/submissions/

def move_num(nums):
	nums.sort()
	ans = 0
	mid = nums[len(nums)//2]
	for num in nums:
		ans += abs(num - mid)