# 747. Largest Number At Least Twice of Others¶

• Time: $O(n)$
• Space: $O(1)$
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 class Solution { public: int dominantIndex(vector& nums) { int ans; int max = 0; int secondMax = 0; for (int i = 0; i < nums.size(); ++i) if (nums[i] > max) { secondMax = max; max = nums[i]; ans = i; } else if (nums[i] > secondMax) { secondMax = nums[i]; } return max >= 2 * secondMax ? ans : -1; } }; 
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 class Solution { public int dominantIndex(int[] nums) { int ans = 0; int max = 0; int secondMax = 0; for (int i = 0; i < nums.length; ++i) if (nums[i] > max) { secondMax = max; max = nums[i]; ans = i; } else if (nums[i] > secondMax) { secondMax = nums[i]; } return max >= 2 * secondMax ? ans : -1; } } 
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 class Solution: def dominantIndex(self, nums: List[int]) -> int: max = 0 secondMax = 0 for i, num in enumerate(nums): if num > max: secondMax = max max = num ans = i elif num > secondMax: secondMax = num return ans if max >= 2 * secondMax else -1