-
Notifications
You must be signed in to change notification settings - Fork 0
/
Infix to Postfix.cpp
92 lines (89 loc) · 1.91 KB
/
Infix to Postfix.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
//{ Driver Code Starts
// C++ implementation to convert infix expression to postfix
#include <bits/stdc++.h>
using namespace std;
// } Driver Code Ends
class Solution
{
public:
// Function to convert an infix expression to a postfix expression.
int prec(char c)
{
if (c == '^')
{
return 3;
}
else if (c == '*' || c == '/')
{
return 2;
}
else if (c == '+' || c == '-')
{
return 1;
}
else
{
return -1;
}
}
string infixToPostfix(string s)
{
string res;
stack<char> st;
for (int i = 0; i < s.length(); i++)
{
if ((s[i] >= 'A' and s[i] <= 'Z') or (s[i] >= 'a' and s[i] <= 'z'))
{
res += s[i];
}
else if (s[i] == '(')
{
st.push(s[i]);
}
else if (s[i] == ')')
{
while (!st.empty() and st.top() != '(')
{
res += st.top();
st.pop();
}
if (!st.empty())
{
st.pop();
}
}
else
{
while (!st.empty() and (prec(s[i]) <= prec(st.top())))
{
res += st.top();
st.pop();
}
st.push(s[i]);
}
}
while (!st.empty())
{
res += st.top();
st.pop();
}
return res;
}
};
//{ Driver Code Starts.
// Driver program to test above functions
int main()
{
int t;
cin >> t;
cin.ignore(INT_MAX, '\n');
while (t--)
{
string exp;
cin >> exp;
Solution ob;
cout << ob.infixToPostfix(exp) << endl;
}
return 0;
}
// } Driver Code Ends