1. Two Sum.go

用hash保存另一个数的值，遍历的同时判断是否存在

func twoSum(nums []int, target int) []int {
    m := make(map[int]int)
    for i := 0; i < len(nums); i++ {
        c, ok := m[nums[i]]
        if ok {
            r := []int{c, i}
            return r
        } else {
            m[target-nums[i]] = i
        }
    }
    r := []int{0, 0}
    return r
}