Leetcode•Sep 10, 2025
Largest Number At Least Twice of Others
Hazrat Ali
Leetcode
Determine whether the largest element in the array is at least twice as much as every other number in the array. If it is, return the index of the largest element, or return -1 otherwise.
Example 1:
Input: nums = [3,6,1,0] Output: 1 Explanation: 6 is the largest integer. For every other number in the array x, 6 is at least twice as big as x. The index of value 6 is 1, so we return 1.
Example 2:
Input: nums = [1,2,3,4] Output: -1 Explanation: 4 is less than twice the value of 3, so we return -1.
Solution
/**
* @param {number[]} nums
* @return {number}
*/
var dominantIndex = function(nums) {
let first = nums[0];
let second = -Infinity;
let maxIndex = 0;
for (let i = 1; i < nums.length; i++) {
if (nums[i] >= first) {
second = first;
first = nums[i];
maxIndex = i;
} else if (nums[i] > second) {
second = nums[i];
}
}
return first >= second * 2 ? maxIndex : -1;
};