括号匹配问题

1。判断括号是否成对出现

 1 import java.util.Stack;  

 2 

 3 public class KuoHao  

 4 {  

 5   

 6     public boolean check(String str)  

 7     {  

 8         Stack<Character> stack = new Stack<Character>();  

 9         boolean flag = true;  

10         for (int i = 0; i < str.length() && flag; i++)  

11         {  

12             try  

13             {  

14                 switch (str.charAt(i))  

15                 {  

16                 case '(':  

17                 case '[':  

18                 case '{':  

19                     stack.push(str.charAt(i));  

20                     break;  

21                 case ')':  

22                     if (stack.pop() != '(')  

23                         flag = false;  

24                     break;  

25                 case ']':  

26                     if (stack.pop() != '[')  

27                         flag = false;  

28                     break;  

29                 case '}':  

30                     if (stack.pop() != '{')  

31                         flag = false;  

32                     break;  

33                 }  

34             }  

35             catch (Exception e)  

36             {  

37                 flag = false;  

38             }  

39         }  

40         if (flag && !stack.isEmpty())  

41             flag = false;  

42   

43         return flag;  

44     }  

45   

46     public static void main(String[] args)  

47     {  

48         KuoHao pm = new KuoHao();  

49         System.out.println("(: " + pm.check("("));  

50         System.out.println("a(bc[d])e{fd}: " + pm.check("a(bc[d])e{fd}"));  

51         System.out.println("a(bc]d: " + pm.check("a(bc]d"));  

52         System.out.println("a(b(c))d: " + pm.check("a(b(c))d"));  

53         System.out.println("a(b)c)d: " + pm.check("a(b)c)d"));  

54     }  

55 }  

2.问题描述：括号成对出现，查找第N个左括号与之匹配的右括号中的内容

　　例如：字符串：A((B)((CD)(E)F)) 查找第1左括号，输出(B)((CD)(E)F)

import java.util.Scanner;



public class KuoHao2 {

	

	public static void search(int N,String s){

		int i = 0,k=-1, w= -1;

		do{

			k = s.indexOf("(",k+1);

			i++;

		}while(i < N && k != -1);

		

		if(k > 0){

			int first = k+1;

			System.out.println("查找字符串\""+s+"\"的第"+N+"个左括号内的内容，匹配起始位于字符串的第:"+(first)+"位");

			w = s.indexOf(")",k+1);

			w = a(w, k, s);

				int end = w;

				System.out.println("匹配结束位于字符串的第:"+(end+1)+"位");

				System.out.println("输出为："+s.substring(first,end ));

			} else {

				System.out.println("不存在')'");

			}

			

		

	}

	



	public static int a(int w, int k, String s){

		if(w > 0){

			int  m =1, n = 1;

			boolean f = false;

			do{

				if(s.indexOf("(",k+1)>0 && s.indexOf("(",k+1) < w){

					k = s.indexOf("(",k+1);

					m += 1;

				}

				while( m > n ){

					while(s.indexOf("(",k+1)>0 && s.indexOf("(",k+1) < w){

						m++;

						k = s.indexOf("(",k+1);

						

					}

					

					for(int j=0; j<=m-n; j++){

						n++;

						w = s.indexOf(")",w+1);

					}

				}

				

				if(s.indexOf("(",k+1)>0 && s.indexOf("(",k+1) < w)

					f = true;

				else f = false;

			}while(f);

		} else {

			System.out.println("不存在'('");

		}

		return w;

	}

		

	public static void main(String[] args) {

		String s = "A((B)((CD)(E)F))";

		Scanner ss =  new Scanner(System.in);

		int N = ss.nextInt();

		search(N,s);

	}



}

　　运行截图：