我本來是陣列所有 item*2 ,然後再逐一比較有沒有大於最大值但這樣要 for 兩次,其實可以找出最大跟第二大就好,若 second*2 > first 那就 return -1 ,一個 for 就可以搞定
/**
* @param {number[]} nums
* @return {number}
*/
var dominantIndex = function(nums) {
let index = 0
let first = nums[index]
let second = -Infinity;
for(let i=1; i< nums.length; i++){
if(nums[i] > first){
second = first
first = nums[i]
index = i
} else if(nums[i] > second && nums[i] < first) {
second = nums[i]
}
}
return first >= second*2 ? index : -1
};