示例 nums = [2, 7, 11, 15], target = 9 nums[0] + nums[1] = 2 + 7 = 9, 输出 [0, 1]
const twoSum = (list, target) => {
for(let i = 0; i < list.length; i++ ){
let temp = target - list[i]
let idx = list.lastIndexOf(temp)
if(idx !== -1 && idx !== i) return [i, idx]
}
}