package main import ( "fmt" "util/stack" ) type tree struct { data int l *tree r *tree } type list struct { data int next *list } //阶乘 func fact(n uint32) uint32 { if n == 0 { return 1 } return n * fact(n-1) } //二分查找 func BSearch(a []int, element, low, height int) int { if low > height { return -1 } mid := (low + height) / 2 if a[mid] == element { return 0 } else if a[mid] > element { return BSearch(a, element, low, mid-1) } else { return BSearch(a, element, mid+1, height) } } //斐波那契数列--递归 func f(n int) int { if n < 3 { return 1 } return f(n-1) + f(n-2) } //斐波那契数列--非递归 func f1(n int) int { var s, s1, s2 int = 1, 1, 1 for i := 3; i <= n; i++ { s = s1 + s2 s2 = s1 s1 = s } return s } //冒泡 func bubblesort(a []int, n int) { //n个数据需要n-1趟 for i := 1; i < n; i++ { //每趟需要比较 元素个数-1 次 for j := 0; j < n-i; j++ { if a[j] > a[j+1] { temp := a[j] a[j] = a[j+1] a[j+1] = temp } } } } //反转链表 func reverseList(head *list) *list { if head == nil { return head } ph := reverseList(head.next) head.next.next = head head.next = nil return ph } func reverseList1(head *list) *list { if head == nil || head.next == nil { return head } node1, node2, node3 := head, head.next, head.next.next for node2 != nil { node2.next = node1 node1.next = nil node1 = node2 node2 = node3 node3 = node3.next } return node2 } //将二叉搜索树转换成双向链表 func treeToDoubleList(head, tail *tree, root *tree) { var ltail, rhead *tree if root == nil { head = nil tail = nil return } treeToDoubleList(head, ltail, root.l) treeToDoubleList(rhead, tail, root.r) if ltail != nil { ltail.r = root root.l = ltail } else { head = root } if rhead != nil { root.r = rhead rhead.l = root } else { tail = root } } //比较两个树是否相等 func compareTree(t1, t2 *tree) int { if t1 == nil && t2 == nil { return 1 } if t1 == nil || t2 == nil { return -1 } if t1.data != t2.data { return -1 } if compareTree(t1.l, t2.l) == 1 && compareTree(t1.r, t2.r) == 1 { return 1 } else { return -1 } } //在二元树中找出和为某一值的所有路径 func getValuePath(root *tree, n int, sum int) { if root == nil { return } s.Push(root.data) sum += root.data if sum == n { fmt.Println(s) s.Pop() return } getValuePath(root.l, n, sum) getValuePath(root.r, n, sum) s.Pop() } //获取最大子数组 func getMaxSubArray(a []int, n int) { if n < 0 || a == nil { return } var sum, begin, end, max int = 0, 0, 0, -1 << 31 for i := 0; i < n; i++ { sum += a[i] if sum < 0 { sum = 0 begin = i + 1 } if sum > max { max = sum end = i } } fmt.Println(begin, end, max) } //判断整数序列是不是二元查找树的后序遍历结果 func checkPostOrder(a []int, l, h int, b *bool) { if l >= h { return } parent := a[h] //fmt.Println(parent, l, h) i := l for ; i < h-1; i++ { if a[i] > parent { break } } for j := i + 1; j < h; j++ { if a[j] <= parent { *b = false break } } if *b { checkPostOrder(a, l, i-1, b) checkPostOrder(a, i, h-1, b) } } //^-反转句子里面单词的顺序 func swap(b []byte, begin, end int) { if begin > end { return } for begin <= end { tmp := b[begin] b[begin] = b[end] b[end] = tmp begin++ end-- } } func reverseStr(str *string) { begin := 0 b := []byte(*str) for i := 0; i < len(*str); i++ { if b[i] == 32 { swap(b, begin, i-1) begin = i + 1 } } swap(b, begin, len(*str)-1) //反转整个字符串 swap(b, 0, len(*str)-1) fmt.Println(string(b)) } //$-反转句子里面单词的顺序 func main() { /* //var b uint32 = 6 //fmt.Println(b, "!=", fact(b)) //a := []int{1, 2, 4, 6, 7, 8, 9, 10, 11, 12} //c := BSearch(a, 4, 0, 9) //fmt.Println(c) //t := []int{3, 2, 1, 5, 7, 6, 9, 0} //bubblesort(t, 8) //fmt.Println(t) //t := []int{1, -2, 3, 10, -4, 7, 2, -5} //getMaxSubArray(t1, len(t1)) t1 := tree{4, nil, nil} t2 := tree{7, nil, nil} t3 := tree{5, &t1, &t2} t4 := tree{12, nil, nil} root := tree{10, &t3, &t4} getValuePath(&root, 22, 0) t := []int{5, 7, 6, 9, 11, 20, 1, 8} //t := []int{7, 4, 6, 5} b := true checkPostOrder(t, 0, 7, &b) fmt.Println(b) */ str := "i am a student." reverseStr(&str) } 有疑问加站长微信联系（非本文作者）
