func twoSum(nums []int, target int) []int {
prevNums := map[int]int{}
for i, num := range nums {
targetNum := target - num
targetNumIndex, found := prevNums[targetNum]
if found {
return []int{targetNumIndex, i}
} else {
prevNums[num] = i
}
}
return []int{}
}
能解释一下targetNumIndex, found := prevNums[targetNum] 这一句话嘛。