add 22

go/backtracking/22/22.括号生成.go

@@ -0,0 +1,187 @@
+/*
+ * @lc app=leetcode.cn id=22 lang=golang
+ *
+ * [22] 括号生成
+ *
+ * https://leetcode.cn/problems/generate-parentheses/description/
+ *
+ * algorithms
+ * Medium (77.55%)
+ * Likes:    3483
+ * Dislikes: 0
+ * Total Accepted:    780.3K
+ * Total Submissions: 1M
+ * Testcase Example:  '3'
+ *
+ * 数字 n 代表生成括号的对数，请你设计一个函数，用于能够生成所有可能的并且 有效的 括号组合。
+ *
+ *
+ *
+ * 示例 1：
+ *
+ *
+ * 输入：n = 3
+ * 输出：["((()))","(()())","(())()","()(())","()()()"]
+ *
+ *
+ * 示例 2：
+ *
+ *
+ * 输入：n = 1
+ * 输出：["()"]
+ *
+ *
+ *
+ *
+ * 提示：
+ *
+ *
+ * 1 <= n <= 8
+ *
+ *
+ */
+package jzoffer
+
+// @lc code=start
+
+func generateParenthesisDFS(n int) (res []string) {
+	var dfs func(path string, l, r int)
+	dfs = func(path string, l, r int) {
+		if l == r && l == n {
+			res = append(res, path)
+			return
+		}
+		if l < r {
+			return
+		}
+		if l < n {
+			dfs(path+"(", l+1, r)
+		}
+		if r < n {
+			dfs(path+")", l, r+1)
+		}
+		return
+	}
+
+	dfs("", 0, 0)
+	return
+}
+
+// 每个位置枚举 所有情况, 实际每个位置就2中情况是'(' 或者 ')',不剪支会超时
+func generateParenthesisEnumDfs(n int) (res []string) {
+	bytes := make([]byte, n*2)
+	for i := 0; i < n; i++ {
+		bytes[i*2] = '('
+		bytes[i*2+1] = ')'
+	}
+
+	check := func(s string) bool {
+		l, r := 0, 0
+		for _, v := range s {
+			if v == '(' {
+				l++
+			} else {
+				r++
+			}
+			if l < r {
+				return false
+			}
+		}
+		return true
+	}
+
+	var dfs func(path []byte, used map[int]bool, idx int)
+	has := make(map[string]bool)
+	dfs = func(path []byte, used map[int]bool, idx int) {
+		if !check(string(path[:idx])) {
+			return
+		}
+		if idx == n*2-1 {
+			if check(string(path)) {
+				if has[string(path)] {
+					return
+				}
+				has[string(path)] = true
+				res = append(res, string(path))
+			}
+			return
+		}
+		l, r := false, false
+		for i := 0; i < len(bytes); i++ {
+			if used[i] {
+				continue
+			}
+			if bytes[i] == '(' {
+				if l {
+					continue
+				}
+				l = true
+			}
+			if bytes[i] == ')' {
+				if r {
+
+					continue
+				}
+				r = true
+			}
+			path[idx] = bytes[i]
+			used[i] = true
+			dfs(path, used, idx+1)
+			used[i] = false
+		}
+	}
+	used := make(map[int]bool)
+	dfs(append([]byte{}, bytes...), used, 0)
+	return
+}
+
+func generateParenthesis(n int) (res []string) {
+	bytes := make([]byte, n*2)
+	for i := 0; i < n; i++ {
+		bytes[i*2] = '('
+		bytes[i*2+1] = ')'
+	}
+
+	check := func(s string) bool {
+		l, r := 0, 0
+		for _, v := range s {
+			if v == '(' {
+				l++
+			} else {
+				r++
+			}
+			if l < r {
+				return false
+			}
+		}
+		return true
+	}
+
+	var dfs func(path []byte, l, r, idx int)
+	has := make(map[string]bool)
+	dfs = func(path []byte, l, r, idx int) {
+		if idx == n*2-1 {
+			if check(string(path)) {
+				if has[string(path)] {
+					return
+				}
+				has[string(path)] = true
+				res = append(res, string(path))
+			}
+			return
+		}
+		if l < n {
+			path[idx] = '('
+			dfs(path, l+1, r, idx+1)
+		}
+
+		if r < n {
+			path[idx] = ')'
+			dfs(path, l, r+1, idx+1)
+		}
+	}
+	dfs(append([]byte{}, bytes...), 0, 0, 0)
+	return
+}
+
+// @lc code=end

go/backtracking/22/22_test.go

@@ -0,0 +1,17 @@
+package jzoffer
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+func Test22(t *testing.T) {
+	now := time.Now()
+	fmt.Println(generateParenthesis(2))
+	fmt.Printf("time:%v\n", time.Since(now).Seconds())
+
+	now = time.Now()
+	fmt.Println(generateParenthesis(6))
+	fmt.Printf("time:%v\n", time.Since(now).Seconds())
+}