leetcode go语言版本，主要为了熟悉下语言
1. Two Sum
双指针版本, O(NlogN)
func twoSum(nums []int, target int) []int {
valResult := []int{}
indexResult := []int{}
i := 0
j := len(nums) - 1
temp := make([]int, len(nums))
copy(temp, nums)
sort.Ints(temp)
for i < j {
if temp[i] + temp[j] < target {
i++
} else if temp[i] + temp[j] > target {
j--
} else {
valResult = append(valResult, temp[i], temp[j])
break
}
}
for i := 0; i < len(nums); i++ {
if nums[i] == valResult[0] || nums[i] == valResult[1] {
indexResult = append(indexResult, i)
}
}
return indexResult
}
hash查找版本，理论O(N)
func twoSum(nums []int, target int) []int {
hash := make(map[int]int)
result := []int{}
for i := 0; i < len(nums); i++ {
if j, ok := hash[target - nums[i]]; ok {
result = append(result, j, i)
return result
}
hash[nums[i]] = i
}
return result
}
2. Add Two Numbers
要想办法把代码写简洁...不要好几个循环判断...
/**
* Definition for singly-linked list.
* type ListNode struct {
* Val int
* Next *ListNode
* }
*/
func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
dummy := ListNode{}
p := &dummy
carry := 0
for l1 != nil || l2 != nil || carry != 0 {
p.Next = &ListNode{}
p = p.Next
tempVal := carry
if l1 != nil {
tempVal += l1.Val
l1 = l1.Next
}
if l2 != nil {
tempVal += l2.Val
l2 = l2.Next
}
p.Val = tempVal % 10
carry = tempVal / 10
}
return dummy.Next
}
3. Longest Substring Without Repeating Characters
hash里面存byte可解决英文字符，存rune中文也可处理...
func lengthOfLongestSubstring(s string) int {
hash := make(map[rune]int)
left := 0
result := 0
for i, v := range []rune(s) {
if lastI, ok := hash[v]; ok && lastI >= left {
left = lastI + 1
}
if result < (i - left + 1) {
result = i - left + 1
}
hash[v] = i
}
return result
}