题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=467
直接上代码：
1 #include <cstdio> 2 #include <cstring> 3 using namespace std; 4 5 const int N = 1001; 6 char stack[N]; 7 char op[N]; 8 char s[N]; 9 int top; 10 int top_op; 11 12 int compare(char a); 13 void translate(); 14 15 int main() 16 { 17 int t; 18 scanf("%d", &t); 19 while(t--) 20 { 21 translate(); 22 } 23 return 0; 24 } 25 26 int compare(char a) 27 { 28 switch(a) 29 { 30 case '+': 31 case '-': 32 return 1; 33 case '*': 34 case '/': 35 return 2; 36 case '(': 37 return 0; 38 default: 39 return -1; 40 } 41 } 42 43 void translate() 44 { 45 scanf("%s", s); 46 int len = strlen(s) - 1; 47 top = -1; 48 top_op = -1; 49 for(int i = 0; i < len; i++) 50 { 51 if('0' <= s[i] && s[i] <= '9' || s[i] == '.') 52 { 53 top++; 54 stack[top] = s[i]; 55 } 56 else if(s[i] == '(') 57 { 58 top_op++; 59 op[top_op] = s[i]; 60 } 61 else if(s[i] == ')') 62 { 63 while(op[top_op] != '(') 64 { 65 top++; 66 stack[top] = ' '; 67 top++; 68 stack[top] = op[top_op]; 69 top_op--; 70 } 71 top_op--; 72 } 73 else if(s[i] == '+' || s[i] == '-' || s[i] == '*' || s[i] == '/') 74 { 75 top++; 76 stack[top] = ' '; 77 if(top_op != -1) 78 { 79 while(compare(s[i]) <= compare(op[top_op])) 80 { 81 top++; 82 stack[top] = op[top_op]; 83 top++; 84 stack[top] = ' '; 85 top_op--; 86 } 87 } 88 top_op++; 89 op[top_op] = s[i]; 90 } 91 } 92 while(top_op != -1) 93 { 94 top++; 95 stack[top] = ' '; 96 top++; 97 stack[top] = op[top_op]; 98 top_op--; 99 } 100 top++; 101 stack[top] = ' '; 102 top++; 103 stack[top] = '='; 104 top++; 105 stack[top] = '\0'; 106 printf("%s\n", stack); 107 }