add new files

Author: anakin

287. Find the Duplicate Number.go

@@ -0,0 +1,21 @@
+package main
+
+func findDuplicate(nums []int) int {
+	left, right := 1, len(nums)-1
+	mid := left + (right-left)/2
+	for left < right {
+		c := 0
+		mid = left + (right-left)/2
+		for i := 0; i < len(nums); i++ {
+			if nums[i] <= mid {
+				c++
+			}
+		}
+		if c > mid {
+			right = mid
+		} else {
+			left = mid + 1
+		}
+	}
+	return left
+}

344. Reverse String.go

@@ -0,0 +1,8 @@
+package main
+
+func reverseString(s []byte) {
+	for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
+		s[i], s[j] = s[j], s[i]
+	}
+
+}

349. Intersection of Two Arrays.go

@@ -0,0 +1,17 @@
+package main
+
+func intersection(nums1 []int, nums2 []int) []int {
+	m := make(map[int]bool)
+	for _, v := range nums1 {
+		m[v] = true
+	}
+
+	ret := []int{}
+	for _, v := range nums2 {
+		if val, ok := m[v]; val && ok {
+			ret = append(ret, v)
+			m[v] = false
+		}
+	}
+	return ret
+}

350. Intersection of Two Arrays II.go

@@ -0,0 +1,23 @@
+package main
+
+func intersect(nums1 []int, nums2 []int) []int {
+	m := make(map[int]int)
+
+	for _, v := range nums1 {
+		if _, ok := m[v]; ok {
+			m[v]++
+		} else {
+			m[v] = 1
+		}
+	}
+
+	ret := []int{}
+
+	for _, v := range nums2 {
+		if val, ok := m[v]; val > 0 && ok {
+			ret = append(ret, v)
+			m[v]--
+		}
+	}
+	return ret
+}

382. Linked List Random Node.go

@@ -0,0 +1,37 @@
+package main
+
+import "math/rand"
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+type Solution struct {
+	count int
+	head  *ListNode
+	pool  []int
+}
+
+/** @param head The linked list's head.
+  Note that the head is guaranteed to be not null, so it contains at least one node. */
+func Constructor(head *ListNode) Solution {
+	var s Solution
+	s.head = head
+	return s
+}
+
+/** Returns a random node's value. */
+func (this *Solution) GetRandom() int {
+	r := rand.Intn(this.count + 1)
+	this.count++
+	if r == this.count-1 && this.head != nil {
+		t := this.head
+		this.head = this.head.Next
+		this.pool = append(this.pool, t.Val)
+		return t.Val
+	} else {
+		return this.pool[r%len(this.pool)]
+	}
+
+}

389. Find the Difference.go

@@ -0,0 +1,23 @@
+package main
+
+//预先把每个字母都装进hash
+func findTheDifference(s string, t string) byte {
+
+	m := make(map[int32]int, 256)
+
+	var i int32
+	for i = 0; i < 256; i++ {
+		m[i] = 0
+	}
+
+	for _, v := range s {
+		m[v]++
+	}
+	for _, v := range t {
+		m[v]--
+		if m[v] < 0 {
+			return byte(v)
+		}
+	}
+	return 0
+}

404. Sum of Left Leaves.go

@@ -0,0 +1,27 @@
+package main
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func sumOfLeftLeaves(root *TreeNode) int {
+	sum := 0
+	if root != nil {
+		if isLeaf(root.Left) {
+			sum += root.Left.Val
+		} else {
+			sum += sumOfLeftLeaves(root.Left)
+		}
+		sum += sumOfLeftLeaves(root.Right)
+	}
+	return sum
+}
+
+func isLeaf(root *TreeNode) bool {
+	if root == nil || root.Left != nil || root.Right != nil {
+		return false
+	}
+	return true
+}

434. Number of Segments in a String.go

@@ -0,0 +1,22 @@
+package main
+
+func countSegments(s string) int {
+
+	count := 1
+	found := false
+	for i := 0; i < len(s); i++ {
+		if i > 0 && s[i] == ' ' && s[i+1] != ' ' {
+			count++
+		}
+		if s[i] != ' ' {
+			found = true
+		}
+		if i == len(s)-1 && s[i] == ' ' {
+			count--
+		}
+	}
+	if found {
+		return count
+	}
+	return 0
+}