关于leetcode:Leetcode刷题笔记第1天

java程序猿转go语言，通过leetcode刷题来相熟go语言，实现语言根底和语法根底的相熟

1.两数之和

暴力破解:

func twoSum(nums []int, target int) []int {    for i := 0; i < len(nums) - 1; i++ {        for j := i + 1; j < len(nums); j++ {            if (nums[j] + nums[i] == target) {                return []int {i, j};            }        }    }    return nil}

哈希表：

func twoSum(nums []int, target int) []int {    hashmap := make(map[int] int)    for index, value := range nums {        if v, ok := hashmap[value]; ok {            return []int{index, v}        }        hashmap[target - value] = index    }    return nil}

2.两数相加

递归版本（链表或者树的问题都要尽量想一个递归的）

 func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {    return addTwoNumbersHelp(l1, l2, 0);}func addTwoNumbersHelp(l1 *ListNode, l2 *ListNode, add int) *ListNode {   if l1 == nil && l2 == nil && add == 0 {      return nil }   if (l1 != nil) {      add = l1.Val + add;      l1 = l1.Next }   if (l2 != nil) {      add = l2.Val + add;      l2 = l2.Next }   node := ListNode{      add % 10,      addTwoNumbersHelp(l1, l2, add / 10),   }   return &node;}

非递归版本

func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {    head := ListNode{};    tail := &head;    add := 0;    for l1 != nil && l2 != nil {        add += l1.Val + l2.Val;        l1 = l1.Next;        l2 = l2.Next;        cur := ListNode{            Val: add % 10,            Next: nil,        }        tail.Next = &cur;        tail = &cur;        add = add / 10;    }    for l1 != nil {        add += l1.Val;        l1 = l1.Next;        cur := ListNode{            Val: add % 10,            Next: nil,        }        tail.Next = &cur;        tail = &cur;        add = add / 10;    }    for l2 != nil {        add += l2.Val;        l2 = l2.Next;        cur := ListNode{            Val: add % 10,            Next: nil,        }        tail.Next = &cur;        tail = &cur;        add = add / 10;    }    if add != 0 {        tail.Next = &ListNode{1,nil}    }    return head.Next;}