Merge pull request #176 from gostool/leetcode0301

add: leetcode 0301 solution

leetcode/0301.Remove-Invalid-Parentheses/301.Remove Invalid Parentheses.go

@@ -0,0 +1,69 @@
+package leetcode
+
+var (
+	res      []string
+	mp       map[string]int
+	n        int
+	length   int
+	maxScore int
+	str      string
+)
+
+func removeInvalidParentheses(s string) []string {
+	lmoves, rmoves, lcnt, rcnt := 0, 0, 0, 0
+	for _, v := range s {
+		if v == '(' {
+			lmoves++
+			lcnt++
+		} else if v == ')' {
+			if lmoves != 0 {
+				lmoves--
+			} else {
+				rmoves++
+			}
+			rcnt++
+		}
+	}
+	n = len(s)
+	length = n - lmoves - rmoves
+	res = []string{}
+	mp = make(map[string]int)
+	maxScore = min(lcnt, rcnt)
+	str = s
+	backtrace(0, "", lmoves, rmoves, 0)
+	return res
+}
+
+func backtrace(i int, cur string, lmoves int, rmoves int, score int) {
+	if lmoves < 0 || rmoves < 0 || score < 0 || score > maxScore {
+		return
+	}
+	if lmoves == 0 && rmoves == 0 {
+		if len(cur) == length {
+			if _, ok := mp[cur]; !ok {
+				res = append(res, cur)
+				mp[cur] = 1
+			}
+			return
+		}
+	}
+	if i == n {
+		return
+	}
+	if str[i] == '(' {
+		backtrace(i+1, cur+string('('), lmoves, rmoves, score+1)
+		backtrace(i+1, cur, lmoves-1, rmoves, score)
+	} else if str[i] == ')' {
+		backtrace(i+1, cur+string(')'), lmoves, rmoves, score-1)
+		backtrace(i+1, cur, lmoves, rmoves-1, score)
+	} else {
+		backtrace(i+1, cur+string(str[i]), lmoves, rmoves, score)
+	}
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}

leetcode/0301.Remove-Invalid-Parentheses/301.Remove Invalid Parentheses_test.go

@@ -0,0 +1,50 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question301 struct {
+	para301
+	ans301
+}
+
+// s 是参数
+type para301 struct {
+	s string
+}
+
+// ans 是答案
+type ans301 struct {
+	ans []string
+}
+
+func Test_Problem301(t *testing.T) {
+
+	qs := []question301{
+
+		{
+			para301{"()())()"},
+			ans301{[]string{"(())()", "()()()"}},
+		},
+
+		{
+			para301{"(a)())()"},
+			ans301{[]string{"(a())()", "(a)()()"}},
+		},
+
+		{
+			para301{")("},
+			ans301{[]string{""}},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 301------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans301, q.para301
+		fmt.Printf("【input】:%v       【output】:%v\n", p, removeInvalidParentheses(p.s))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0301.Remove-Invalid-Parentheses/README.md

@@ -0,0 +1,55 @@
+# [301. Remove Invalid Parentheses](https://leetcode-cn.com/problems/remove-invalid-parentheses/)
+
+
+## 题目
+
+Given a string s that contains parentheses and letters, remove the minimum number of invalid parentheses to make the input string valid.
+
+Return all the possible results. You may return the answer in any order.
+
+**Example 1:**
+
+    Input: s = "()())()"
+    Output: ["(())()","()()()"]
+
+**Example 2:**
+
+    Input: s = "(a)())()"
+    Output: ["(a())()","(a)()()"]
+
+**Example 3:**
+
+    Input: s = ")("
+    Output: [""]
+
+**Constraints:**
+
+- 1 <= s.length <= 25
+- s consists of lowercase English letters and parentheses '(' and ')'.
+- There will be at most 20 parentheses in s.
+
+## 题目大意
+
+给你一个由若干括号和字母组成的字符串 s ，删除最小数量的无效括号，使得输入的字符串有效。
+
+返回所有可能的结果。答案可以按 任意顺序 返回。
+
+说明:
+
+- 1 <= s.length <= 25
+- s 由小写英文字母以及括号 '(' 和 ')' 组成
+- s 中至多含 20 个括号
+
+
+## 解题思路
+
+回溯和剪枝
+- 计算最大得分数maxScore，合法字符串的长度length，左括号和右括号的移除次数lmoves,rmoves
+- 加一个左括号的得分加1；加一个右括号的得分减1
+- 对于一个合法的字符串，左括号等于右括号，得分最终为0；
+- 搜索过程中出现以下任何一种情况都直接返回
+    - 得分值为负数
+    - 得分大于最大得分数
+    - 得分小于0
+    - lmoves小于0
+    - rmoves小于0