Valid_Parentheses.cpp

本文介绍了一个使用栈数据结构实现的有效括号匹配验证算法。该算法能够判断字符串中的括号是否正确配对,包括圆括号、方括号及花括号。通过遍历输入字符串并利用栈来跟踪开括号,当遇到闭括号时检查栈顶元素是否为对应的开括号。最终若栈为空则说明所有括号均已正确配对。

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<span style="font-size:18px;">/*************************************************************************
	> File Name: Valid_Parentheses.cpp
	> Author: 
	> Mail: 
	> Created Time: 2014年08月24日 星期日 14时54分19秒
 ************************************************************************/
/*************************************************************************
  Description:

  Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

  The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

**************************************************************************/

#include<iostream>
#include<stdio.h>
#include<stack>
#include<string.h>
using namespace std;

stack<char>Stack;
bool Solution(const char *str)
{
    if(str == NULL)
    {
        return false;
    }

    int len = strlen(str);
    while(*str != '\0')
    {
        if((*str == '{')|| (*str == '[') || (*str == '('))
        {
            Stack.push(*str);
            str++;
        }
        if(*str == '}')
        {
            if(!Stack.empty())
            {
                 if(Stack.top() == '{')
                 {
                     Stack.pop();
                 }
                else
                     return false;
            }
            else
            {
                return false;    
            }
            str++;
        }

        if(*str == ']')
        {
            if(!Stack.empty())
            {
                 if(Stack.top() == '[')
                 {
                     Stack.pop();
                 }
                else
                     return false;
            }
            else
            {
                return false;    
            }
            str++;
        }

        if(*str == ')')
        {
            if(!Stack.empty())
            {
                 if(Stack.top() == '(')
                 {
                     Stack.pop();
                 }
                else
                    return false;
            }
            else
            {
                return false;    
            }
            str++;
        }
    }
    if(!Stack.empty())
    {
        return false;
    }
    else
    {
        return true;

    } 
}


int main()
{
   const  char *str = "}";
   if(Solution(str))
        printf("OK");
   else
        printf("NO");
}</span>

#include <cassert> /// for assert #include <iostream> /// for I/O operation #include <vector> /// for vector container /** @brief Backtracking algorithms @namespace backtracking / namespace backtracking { /* @brief generate_parentheses class */ class generate_parentheses { private: std::vectorstd::string res; ///< Contains all possible valid patterns void makeStrings(std::string str, int n, int closed, int open); public: std::vectorstd::string generate(int n); }; /** @brief function that adds parenthesis to the string. @param str string build during backtracking @param n number of pairs of parentheses @param closed number of closed parentheses @param open number of open parentheses */ void generate_parentheses::makeStrings(std::string str, int n, int closed, int open) { if (closed > open) // We can never have more closed than open return; if ((str.length() == 2 * n) && (closed != open)) { // closed and open must be the same return; } if (str.length() == 2 * n) { res.push_back(str); return; } makeStrings(str + ')', n, closed + 1, open); makeStrings(str + '(', n, closed, open + 1); } /** @brief wrapper interface @param n number of pairs of parentheses @return all well-formed pattern of parentheses */ std::vectorstd::string generate_parentheses::generate(int n) { backtracking::generate_parentheses::res.clear(); std::string str = “(”; generate_parentheses::makeStrings(str, n, 0, 1); return res; } } // namespace backtracking /** @brief Self-test implementations @returns void */ static void test() { int n = 0; std::vectorstd::string patterns; backtracking::generate_parentheses p; n = 1; patterns = {{“()”}}; assert(p.generate(n) == patterns); n = 3; patterns = {{“()()()”}, {“()(())”}, {“(())()”}, {“(()())”}, {“((()))”}}; assert(p.generate(n) == patterns); n = 4; patterns = {{“()()()()”}, {“()()(())”}, {“()(())()”}, {“()(()())”}, {“()((()))”}, {“(())()()”}, {“(())(())”}, {“(()())()”}, {“(()()())”}, {“(()(()))”}, {“((()))()”}, {“((())())”}, {“((()()))”}, {“(((())))”}}; assert(p.generate(n) == patterns); std::cout << “All tests passed\n”; } /** @brief Main function @returns 0 on exit */ int main() { test(); // run self-test implementations return 0; } 在这段代码的基础上为C++初学者出几个练习题?
最新发布
03-08
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