Data Structure Problems

infix to postfix.cpp

#include <bits/stdc++.h>

using namespace std;

int check_precedence(char op)
{
    switch (op)
    {
    case '+':
    case '-':
        return 1;
        break;
    case '*':
    case '/':
        return 2;
        break;
    case '^':
        return 3;
        break;
    }
    return 0;
}

string infixToPostfix(string in)
{
    string out;
    stack<char> op;
    for (int i = 0; i < in.size(); i++)
    {
        switch (in[i])
        {
        case '*':
        case '/':
        case '+':
        case '-':
            if(op.empty())
                op.push(in[i]);
            else
            {
                if(check_precedence(op.top()) < check_precedence(in[i]))
                    op.push(in[i]);
                else
                {
                    out += op.top();
                    op.pop();
                    op.push(in[i]);
                }
            }
            break;
        case '(':
            op.push(in[i]);
            break;
        case ')':
            while(op.top() != '(')
            {
                out += op.top();
                op.pop();
            }
            op.pop();
            break;
        default:
            out += in[i];
            break;
        }
    }
    
    while (!op.empty())
    {
        out+= op.top();
        op.pop();
    }

    return out;
}

int main()
{
    string in;
    cin >> in;    
    
    cout << infixToPostfix(in) << '\n';

    return 0;
}

sequence.cpp

#include <bits/stdc++.h>

using namespace std;

int main()
{
    vector<int> seq;
    bool dec=0, valid = 1;
    
    int n;
    cin >> n;

    int tmp;
    cin >> tmp;
    seq.push_back(tmp);
    n--;

    while (n--)
    {
        cin >> tmp;

        if(dec == 0)
        {
            if(seq[seq.size() -1] < tmp)
                seq.push_back(tmp);
            else
                dec = 1;
        }

        if(dec == 1)
        {
            if(seq[seq.size() -1] > tmp && find(seq.begin(), seq.end(), tmp) != seq.end())
            {
                seq.push_back(tmp);
            }
            else
            {
                valid = 0;
                break;
            }
        }
    }
    if(valid)
        cout << "Yes\n";
    else
        cout << "No\n";
    return 0;
}