I. Title Description:

20. Effective brackets given a include only ‘(‘,’) ‘, ‘{‘,’} ‘, ‘/’, ‘ ‘the string s, determine whether a string is effective.

A valid string must meet the following requirements:

  1. An open parenthesis must be closed with a close parenthesis of the same type.
  2. The left parentheses must be closed in the correct order.

Example 1:

Input: s = “()” output: true

Example 2:

Input: s = “()[]{}” Output: true

Example 3:

Input: s = “(]” Output: false

Example 4:

Input: s = “([)]” Output: false

Example 5:

Input: s = “{[]}” Output: true

Ii. Analysis of Ideas:

  • Declare an array ARR to store the elements of a string
  • Determine if the last element of arr and s.charat (I) form a pair of parentheses as you traverse the string.
  • Arr.pop () if a pair of parentheses can be formed.
  • Otherwise the arr. Push (s.c harAt (I)).
  • Finally, check whether the array is empty, and if it iss 是 Valid parenthesesOtherwise it is not

Iii. AC Code:

/ * * *@param {string} s
 * @return {boolean}* /
var isValid = function(s) {
    let arr = s? [s.charAt(0] : [];for(let i = 1; i < s.length; i++) {
        let str = s.charAt(i);
        switch(str) {
            case '] ':
                str = '[';
                break;
            case '} ':
                str = '{';
                break;
            case ') ':
                str = '(';
                break;
        }
        if(arr[arr.length - 1] === str && s.charAt(i) ! == str) { arr.pop(); }else{ arr.push(s.charAt(i)); }}return arr.length === 0
};
Copy the code

Iv. Summary:

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