文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

Largest Number At Least Twice of Others

2. Solution

• Version 1

class Solution {
public:
    int dominantIndex(vector<int>& nums) {
        int index = 0;
        for(int i = 1; i < nums.size(); i++) {
            if(nums[i] > nums[index]) {
                index = i;
            }
        }
        for(int i = 0; i < nums.size(); i++) {
            if(index != i && nums[i] * 2 > nums[index]) {
                return -1;
            }
        }
        return index;
    }
};

• Version 2

class Solution {
public:
    int dominantIndex(vector<int>& nums) {
        if(nums.size() == 1) {
            return 0;
        }
        int index = 0;
        int second = 1;
        for(int i = 1; i < nums.size(); i++) {
            if(nums[i] > nums[index]) {
                second = index;
                index = i;
            }
            else if(nums[i] > nums[second]) {
                second = i;
            }
        }
        if(nums[second] * 2 > nums[index]) {
            return -1;
        }
        return index;
    }
};

Reference

1. https://leetcode.com/problems/largest-number-at-least-twice-of-others/description/