n对括号的所有有效组合 [英] all valid combinations of n-pair of parenthesis

问题描述

• 我正在学习js ..
  
  
  
  • 我正在尝试编写一个简单的js程序..
  
  
  • 我要做的是打印n对
    括号的所有有效组合（正确打开和关闭）
  
  
  • 例如（），（（）（ ）），（（））
  
  
  • 我写的逻辑可以告诉我它是否正确
  
  
  • I am learning js now..
    • I am trying to write a simple js programme..
    • what I am trying to do is to print all valid combinations of n-pair of parenthesis(properly opened and closed)
    • eg (), (()()),(())
    • i have written the logic can you tell me whether its correct or not

    https://jsfiddle.net/e7mcp6xb/

    module.exports = Parentheses = (function() {
      var _isParenthesesMatch = function(str) {
        var parentheses = str.length;
        var rightParentheses = '(';
        var leftParentheses = ')';
        var rightCount = 0;
        var leftCount = 0;
    
        for(i=0;i<=str.length;i++){
           if(rightParentheses == str.charAt(i))
           {
              rightCount++;
           }
           else if(leftParentheses == str.charAt(i))
           {
              leftCount++;
           }
        }
    
        if(rightCount == leftCount){
          return true;
        }
        else(rightCount != leftCount){
          return false;
        }
    
      }
    
    }());
    

    
    

    推荐答案

    检查错误，但您可以轻松修复：在 for 循环的每一步中，左括号的数量不能小于结束数量：

    The check is wrong, but You can fix it easily: In each step of the for loop the number of opening parenthesis cannot be smaller than the number of closing ones:

    if (rightCount < leftCount)
        return false;
    

    整个函数应如下所示：

    function(str) {
        var rightParentheses = '(';
        var leftParentheses = ')';
        var rightCount = 0;
        var leftCount = 0;
    
        for (var i = 0; i <= str.length; i++) {
           if (rightParentheses == str.charAt(i))
              rightCount++;
           else if (leftParentheses == str.charAt(i))
              leftCount++;
    
           if (rightCount < leftCount)
              return false;
        }
    
        return rightCount == leftCount;
    }
    

    如果您想生成所有有效字符串，可以使用此功能：

    If You'd like to generate all valid strings, you can use this function:

    function nPair(n) {
        if (n == 0)
            return [""];
    
        var result = [];
        for (var i = 0; i < n; ++i) {
    
            var lefts = nPair(i);
            var rights = nPair(n - i - 1);
    
            for (var l = 0; l < lefts.length; ++l)
                for (var r = 0; r < rights.length; ++r)
                    result.push("(" + lefts[l] + ")" + rights[r]);
        }
    
        return result;
    }
    
    // result of nPair(3):
    // ["()()()", "()(())", "(())()", "(()())", "((()))"]
    

    这篇关于n对括号的所有有效组合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！