|
| 1 | + |
| 2 | + |
| 3 | + |
| 4 | +>仰望星空的人,不应该被嘲笑 |
| 5 | + |
| 6 | +## 题目描述 |
| 7 | + |
| 8 | + |
| 9 | +给定一个只包括` '(',')','{','}','[',']' `的字符串,判断字符串是否有效。 |
| 10 | + |
| 11 | +有效字符串需满足: |
| 12 | + |
| 13 | +左括号必须用相同类型的右括号闭合。 |
| 14 | +左括号必须以正确的顺序闭合。 |
| 15 | +注意空字符串可被认为是有效字符串。 |
| 16 | + |
| 17 | +示例 1: |
| 18 | + |
| 19 | +```javascript |
| 20 | +输入: "()" |
| 21 | +输出: true |
| 22 | +``` |
| 23 | + |
| 24 | +示例 2: |
| 25 | + |
| 26 | +```javascript |
| 27 | +输入: "()[]{}" |
| 28 | +输出: true |
| 29 | +``` |
| 30 | + |
| 31 | +示例 3: |
| 32 | + |
| 33 | +```javascript |
| 34 | +输入: "(]" |
| 35 | +输出: false |
| 36 | +``` |
| 37 | + |
| 38 | +示例 4: |
| 39 | + |
| 40 | +```javascript |
| 41 | +输入: "([)]" |
| 42 | +输出: false |
| 43 | +``` |
| 44 | + |
| 45 | +示例 5: |
| 46 | + |
| 47 | +```javascript |
| 48 | +输入: "{[]}" |
| 49 | +输出: true |
| 50 | +``` |
| 51 | + |
| 52 | + |
| 53 | +## 题解 |
| 54 | + |
| 55 | +发现越靠后的左括号,最先匹配,也就是`后进先出`的思想,于是考虑使用栈这个数据结构。 |
| 56 | + |
| 57 | +```javascript |
| 58 | +/** |
| 59 | + * @param {string} s |
| 60 | + * @return {boolean} |
| 61 | + */ |
| 62 | +var isValid = function(s) { |
| 63 | + // 如果是奇数,不可能匹配成功,直接返回false |
| 64 | + if(s.length & 1) return false |
| 65 | + let stack = [] |
| 66 | + for(let i=0;i<s.length;i++){ |
| 67 | + if(s[i] === '(' || s[i] === '{' || s[i] === '[') stack.push(s[i]) |
| 68 | + else if(s[i] === ')' && stack[stack.length-1] === '(') stack.pop() |
| 69 | + else if(s[i] === '}' && stack[stack.length-1] === '{') stack.pop() |
| 70 | + else if(s[i] === ']' && stack[stack.length-1] === '[') stack.pop() |
| 71 | + else return false |
| 72 | + } |
| 73 | + return !stack.length |
| 74 | +}; |
| 75 | +``` |
| 76 | + |
| 77 | + |
| 78 | + |
| 79 | +## 最后 |
| 80 | +文章产出不易,还望各位小伙伴们支持一波! |
| 81 | + |
| 82 | +往期精选: |
| 83 | + |
| 84 | +<a href="https://github.com/Chocolate1999/Front-end-learning-to-organize-notes">小狮子前端の笔记仓库</a> |
| 85 | + |
| 86 | +<a href="https://yangchaoyi.vip/">访问超逸の博客</a>,方便小伙伴阅读玩耍~ |
| 87 | + |
| 88 | + |
| 89 | + |
| 90 | +```javascript |
| 91 | +学如逆水行舟,不进则退 |
| 92 | +``` |
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