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Author: anakin

160. Intersection of Two Linked Lists.go

@@ -0,0 +1,34 @@
+package main
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+//两个指针，先计算长度，相遇的时候，两个链表的长度一致
+func getIntersectionNode(headA, headB *ListNode) *ListNode {
+	a, b := headA, headB
+	la, lb := 0, 0
+	for a != nil {
+		a = a.Next
+		la++
+	}
+	for b != nil {
+		b = b.Next
+		lb++
+	}
+	a, b = headA, headB
+	for la < lb {
+		b = b.Next
+		b--
+	}
+	for lb < la {
+		a = a.Next
+		a--
+	}
+	for a != b {
+		a = a.Next
+		b = b.Next
+	}
+	return a
+}

162. Find Peak Element.go

@@ -0,0 +1,21 @@
+package main
+
+//不难，就是要注意首尾的判断
+func findPeakElement(nums []int) int {
+	l := len(nums)
+	if l == 1 {
+		return 0
+	}
+	if nums[0] > nums[1] { //第一个元素
+		return 0
+	} else if nums[l-1] > nums[l-2] { //最后一个元素
+		return l - 1
+	} else { //中间的
+		for i := 1; i < len(nums)-1; i++ {
+			if nums[i] > nums[i-1] && nums[i] > nums[i+1] {
+				return i
+			}
+		}
+	}
+	return -1
+}

167. Two Sum II - Input array is sorted.go

@@ -0,0 +1,16 @@
+package main
+
+//从两端向中间收敛
+func twoSum(numbers []int, target int) []int {
+	l, r := 0, len(numbers)-1
+	for l < r {
+		if numbers[l]+numbers[r] < target {
+			l++
+		} else if numbers[l]+numbers[r] > target {
+			r--
+		} else {
+			return []int{l + 1, r + 1}
+		}
+	}
+	return nil
+}

169. Majority Element.go

@@ -0,0 +1,19 @@
+package main
+
+//NB
+func majorityElement(nums []int) int {
+	c := nums[0]
+	count := 1
+	for i := 1; i < len(nums); i++ {
+		if nums[i] == c {
+			count++
+		} else {
+			count--
+		}
+		if count < 1 {
+			count = 1
+			c = nums[i]
+		}
+	}
+	return c
+}

179. Largest Number.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"sort"
+	"strconv"
+)
+
+//用内置排序接口
+type intSlice []int
+
+func newIntSlice(a []int) intSlice {
+	b := intSlice{}
+	for _, v := range a {
+		b = append(b, v)
+	}
+	return b
+}
+func (s intSlice) Len() int {
+	return len(s)
+}
+
+func (s intSlice) Less(i, j int) bool {
+	stri := strconv.Itoa(s[i])
+	strj := strconv.Itoa(s[j])
+	s1, _ := strconv.Atoi(stri + strj)
+	s2, _ := strconv.Atoi(strj + stri)
+	return s1 > s2
+}
+
+func (s intSlice) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func largestNumber(nums []int) string {
+	s := newIntSlice(nums)
+	sort.Sort(s)
+	res := ""
+	for _, v := range s {
+		res += strconv.Itoa(v)
+		if res == "0" {
+			res = ""
+		}
+	}
+	if res == "" {
+		return "0"
+	}
+	return res
+}

189. Rotate Array.go

@@ -0,0 +1,17 @@
+package main
+
+func rotate(nums []int, k int) {
+	if k == 0 || len(nums) == 0 {
+		return
+	}
+	k = k % len(nums)
+	if k == 0 {
+		return
+	}
+	tmp := nums
+	nums = append(nums[len(nums)-k:], nums[0:len(nums)-k]...)
+	for i := 0; i < len(tmp); i++ {
+		tmp[i] = nums[i]
+	}
+	return
+}

203. Remove Linked List Elements.go

@@ -0,0 +1,19 @@
+package main
+
+//双指针
+func removeElements(head *ListNode, val int) *ListNode {
+	if head == nil {
+		return head
+	}
+	var p1 ListNode
+	p1.Next = head
+	p2 := &p1
+	for head != nil {
+		if head.Val == val {
+			p2.Next, head = head.Next, head.Next
+		} else {
+			p2, head = head, head.Next
+		}
+	}
+	return p1.Next
+}

206. Reverse Linked List.go

@@ -0,0 +1,15 @@
+package main
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func reverseList(head *ListNode) *ListNode {
+	var newh ListNode
+	for head != nil {
+		newh.Next, head.Next, head = head, newh.Next, head.Next
+	}
+	return newh.Next
+
+}

217. Contains Duplicate.go

@@ -0,0 +1,16 @@
+package main
+
+func containsDuplicate(nums []int) bool {
+	if len(nums) < 2 {
+		return false
+	}
+	m := make(map[int]bool)
+	for _, v := range nums {
+		_, ok := m[v]
+		if ok {
+			return true
+		}
+		m[v] = true
+	}
+	return false
+}

219. Contains Duplicate II.go

@@ -0,0 +1,19 @@
+package main
+
+//找到的时候判断一下距离
+func containsNearbyDuplicate(nums []int, k int) bool {
+	if len(nums) < 2 {
+		return false
+	}
+	m := make(map[int]int)
+	for i, v := range nums {
+		val, ok := m[nums[i]]
+		if ok {
+			if val+k >= i {
+				return true
+			}
+		}
+		m[v] = i
+	}
+	return false
+}