直接用棧模擬即可，數組可做，但因為這節數據結構是棧，為了期末考試還是手寫一下棧的操作，值得註意的是，這道題用gets函數在PTA上會編譯錯誤，用scanf("%[^\n]", str)會有一個樣例無法通過，最後我使用了string讀入數據，應該是我對scanf格式化讀入不夠了解，有知道的朋友可以評論區告訴我，非常感謝

附上代碼：

  1 #include <stdio.h>
  2 #include <malloc.h>
  3 #include <stdlib.h>
  4 #include <string.h>
  5 
  6
 
 #include <iostream>
  7 #include <string>
  8 
  9 using namespace std;
 10 
 11 //函數狀態碼定義
 12 #define TRUE        1
 13 #define FALSE       0
 14 #define OK          1
 15 #define ERROR       0
 16 #define INFEASIBLE -1
 17 #define OVERFLOW   -2
 18 
 19 typedef int Status;
 20
 
 typedef char SElemType;
 21 
 22 #define STACK_INIT_SIZE 500
 23 #define STACKINCREMENT 10
 24 
 25 typedef struct {
 26     SElemType *base;
 27     SElemType *top;
 28     int stacksize;
 29 }SqStack;
 30 
 31 Status InitStack(SqStack &S) {
 32     S.base = (SElemType * )malloc(STACK_INIT_SIZE * sizeof
 
(SElemType));
 33     if(!S.base) exit(OVERFLOW);
 34     S.top = S.base;
 35     S.stacksize = STACK_INIT_SIZE;
 36     return OK;
 37 }//InitStack
 38 
 39 Status GetTop(SqStack &S, SElemType &e) {
 40     if(S.top == S.base)
 41         return ERROR;
 42     e = *(S.top - 1);
 43     return OK;
 44 }//GetTop
 45 
 46 Status Push(SqStack &S, SElemType e) {
 47     if(S.top - S.base >= S.stacksize) {
 48         S.base = (SElemType * )realloc(S.base, (S.stacksize + STACKINCREMENT) * sizeof(SElemType));
 49         if(!S.base)
 50             exit(OVERFLOW);
 51         S.top = S.base + S.stacksize;
 52         S.stacksize += STACKINCREMENT;
 53     }
 54     *S.top++ = e;
 55     return OK;
 56 }//Push
 57 
 58 Status Pop(SqStack &S, SElemType &e) {
 59     if(S.top == S.base)
 60         return ERROR;
 61     e = *--S.top;
 62     return OK;
 63 }//Pop
 64 
 65 char change(char ch){
 66     if(ch == ‘(‘)
 67         return ‘)‘;
 68     if(ch == ‘{‘)
 69         return ‘}‘;
 70     if(ch == ‘[‘)
 71         return ‘]‘;
 72     if(ch == ‘a‘)
 73         return ‘b‘;
 74     if(ch == ‘)‘)
 75         return ‘(‘;
 76     if(ch == ‘}‘)
 77         return ‘{‘;
 78     if(ch == ‘]‘)
 79         return ‘[‘;
 80     if(ch == ‘b‘)
 81         return ‘a‘;
 82 };
 83 
 84 int main()
 85 {
 86     SqStack sta;
 87     InitStack(sta);
 88 
 89     char ch, ptr[200] = {0}, cnt = 0;
 90 
 91     char ans = ‘ ‘; // ( -> 1, { -> 2, [ -> 3, /* -> 4
 92 
 93     string str;
 94 
 95     while(getline(cin, str)) {
 96         if(str == ".")
 97             break;
 98         for(int i = 0; i < str.size(); ++i) {
 99             if(str[i] == ‘(‘ || str[i] == ‘{‘ || str[i] == ‘[‘ || str[i] == ‘)‘ || str[i] == ‘}‘ || str[i] == ‘]‘)
100                 ptr[cnt++] = str[i];
101             else if(str[i] == ‘/‘ && str[i + 1] == ‘*‘)
102                 ptr[cnt++] = ‘a‘, ++i;
103             else if(str[i] == ‘*‘ && str[i + 1] == ‘/‘)
104                 ptr[cnt++] = ‘b‘, ++i;
105         }
106     }
107 
108     for(int i = 0; i < cnt; ++i) {
109         if(ptr[i] == ‘(‘ || ptr[i] == ‘{‘ || ptr[i] == ‘[‘ || ptr[i] == ‘a‘)
110             Push(sta, ptr[i]);
111         else {
112             if(GetTop(sta, ch) == OK) {
113                 if(ptr[i] == change(ch)) {
114                     Pop(sta, ch);
115                 }
116                 else {
117                     ans = ch;
118                     break;
119                 }
120             }
121             else {
122                 ans = ptr[i];
123                 break;
124             }
125         }
126     }
127 
128     if(ans == ‘ ‘ && GetTop(sta, ch) == OK) {
129         ans = ch;
130     }
131 
132     if(ans == ‘ ‘)
133         printf("YES");
134     else {
135         printf("NO\n");
136         if(ans == ‘(‘ || ans == ‘{‘ || ans == ‘[‘)
137             printf("%c-?",ans);
138         else if(ans == ‘a‘)
139             printf("/*-?");
140         else if(ans == ‘)‘ || ans == ‘}‘ || ans == ‘]‘)
141             printf("?-%c",ans);
142         else
143             printf("?-*/");
144     }
145 
146     return 0;
147 }

PTA 7-2 符號配對