# LeetCode - 0747. Largest Number At Least Twice of Others
### 題目網址：https://leetcode.com/problems/largest-number-at-least-twice-of-others/
###### tags: `LeetCode` `Easy`

/*
    -LeetCode format-
    Problem: 747. Largest Number At Least Twice of Others
    Difficulty: Easy
    
    by Inversionpeter
*/



class Solution {
public:
    int dominantIndex(vector<int>& nums) {
        int first = nums[0], second = -1, firstAt = 0;
        for (int i = 1; i != nums.size(); ++i) {
            if (first == nums[i] || second == nums[i])
                continue;
            if (first < nums[i]) 
                second = first, first = nums[i], firstAt = i;
            else if (second < nums[i]) 
                second = nums[i];
        }
        return (second == -1 || first >= (second << 1) ? firstAt : -1);
    }
};