nyist oj 467 （中缀式变后缀式）

#include <cstdio>
#include <cstring>
using namespace std;

const int N = 1001;
char stack
;
char op
;
char s
;
int top;
int top_op;

int compare(char a);
void translate();

int main()
{
int t;
scanf("%d", &t);
while(t--)
{
translate();
}
return 0;
}

int compare(char a)
{
switch(a)
{
case '+':
case '-':
return 1;
case '*':
case '/':
return 2;
case '(':
return 0;
default:
return -1;
}
}

void translate()
{
scanf("%s", s);
int len = strlen(s) - 1;
top = -1;
top_op = -1;
for(int i = 0; i < len; i++)
{
if('0' <= s[i] && s[i] <= '9' || s[i] == '.')
{
top++;
stack[top] = s[i];
}
else if(s[i] == '(')
{
top_op++;
op[top_op] = s[i];
}
else if(s[i] == ')')
{
while(op[top_op] != '(')
{
top++;
stack[top] = ' ';
top++;
stack[top] = op[top_op];
top_op--;
}
top_op--;
}
else if(s[i] == '+' || s[i] == '-' || s[i] == '*' || s[i] == '/')
{
top++;
stack[top] = ' ';
if(top_op != -1)
{
while(compare(s[i]) <= compare(op[top_op]))
{
top++;
stack[top] = op[top_op];
top++;
stack[top] = ' ';
top_op--;
}
}
top_op++;
op[top_op] = s[i];
}
}
while(top_op != -1)
{
top++;
stack[top] = ' ';
top++;
stack[top] = op[top_op];
top_op--;
}
top++;
stack[top] = ' ';
top++;
stack[top] = '=';
top++;
stack[top] = '\0';
printf("%s\n", stack);
}