632A - Grandma Laura and Apples - CodeForces Solution

#define imax INT_MAX
#define imin INT_MIN
#define sz(x) (int((x).size()))
#define ll long long
#define pb push_back
#define mk make_pair
#define pii pair<int, int>
#define a first
#define b second
#define vi vector<int>
#define over(x) (x).begin(), (x).end()
#define umap unordered_map
#define uset unordered_set
#define MOD 1000000007

#include <algorithm>
#include <bits/stdc++.h>
#include <iostream>
#include <queue>
#include <stdio.h>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

struct node {
    int val;
    node *next;
    node *prev;
};

struct VectorHasher {
    int operator()(const vector<int> &V) const {
        int hash = V.size();
        for (auto &i : V) {
            hash ^= i + 0x9e3779b9 + (hash << 6) + (hash >> 2);
        }
        return hash;
    }
};

struct PairHasher {
    size_t operator()(const pii &x) const { return x.first ^ x.second; }
};

void solve(int s) { cout << s << endl; }

int main(void) {

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    /* number of test cases, remember to check bounds*/
    unsigned int t;
    unsigned int n;

#ifndef ONLINE_JUDGE
    freopen("../input.txt", "r", stdin);
    freopen("../output.txt", "w", stdout);
#endif
    int p;
    cin >> t >> p;
    vector<string> nums;
    for (int i = 0; i < t; ++i) { // loops for each case
        string s;
        cin >> s;
        nums.pb(s);
    }
    ll ans = p/2;
    ll cur = 1;
    for(int i=sz(nums)-2;i>=0;--i){
        if(nums[i] == "half"){
            ans += p*cur;
            cur *= 2;
        }else{
            ans += p*cur+p/2;
            cur = cur*2+1;
        }
    }
    cout << ans << endl;
    return 0;
}