Problem - 922D、Robot Vacuum Cleaner - Codeforces

Pushok the dog has been chasing Imp for a few hours already.

Fortunately, Imp knows that Pushok is afraid of a robot vacuum cleaner.While moving, the robot generates a string t consisting of letters ‘s’ and ‘h’, that produces a lot of noise. We define noise of string t as the number of occurrences of string “sh” as a subsequence in it, in other words, the number of such pairs (i, j), that i < j and and .The robot is off at the moment. Imp knows that it has a sequence of strings ti in its memory, and he can arbitrary change their order. When the robot is started, it generates the string t as a concatenation of these strings in the given order. The noise of the resulting string equals the noise of this concatenation.Help Imp to find the maximum noise he can achieve by changing the order of the strings.

Input

The first line contains a single integer n (1 ≤ n ≤ 105) — the number of strings in robot’s memory.Next n lines contain the strings t1, t2, …, tn, one per line. It is guaranteed that the strings are non-empty, contain only English letters ‘s’ and ‘h’ and their total length does not exceed 105.

Output

Print a single integer — the maxumum possible noise Imp can achieve by changing the order of the strings.

Examples

input

4
ssh
hs
s
hhhs

output

18

Problem analysis

The question is , Here you are. n A string , These strings are all composed of characters ’s’ and ‘h’ Composed of . Let you combine these strings in any order , Make the string contain ’sh‘ Subsequences are at most .

About this problem , It uses a kind of called “ Neighborhood exchange ” Written by , The idea is like this ： Two strings a and b, If a+b The composed string contains ’sh‘ Subsequence ratio b+a The string consists of many , Then when you finally splice a Put it in b The former is a better choice . So this method is to write a cmp then sort Just a moment .

cmp The content is to combine the two strings in different order , Calculate what they contain respectively ’sh‘ Number , as for ’sh‘ Number of sequences , It's every one h All before the character s The number of characters adds up . Pay attention to the , If two strings of ’sh‘ The number of sequences is equal , Then go back false（ I don't know why , But that's it , Otherwise re）.

AC Code

#include<iostream>
using namespace std;
#include<vector>
#include<algorithm>
#include<math.h>
#include<set>
#include<numeric>
#include<string>
#include<string.h>
#include<iterator>
#include<map>
#include<unordered_map>
#include<stack>
#include<list>
#include<queue>
#include<iomanip>

#define endl '\n'
#define int ll
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll>PII;
const int N = 2e5 + 50;

int get_sh(string& s)
{
    int cnt = 0, nums = 0, numh = 0;
    for (auto i : s)
    {
        if (i == 's')
        {
            nums++;
        }
        else
        {
            numh++;
            cnt += nums;
        }
    }
    return cnt;
}

bool cmp(string a, string b)
{
    string s1 = a + b, s2 = b + a;
    return get_sh(s1)>get_sh(s2);
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n;
    cin >> n;
    vector<string>v(n);
    for (int i = 0; i < n; i++)
        cin >> v[i];
    sort(v.begin(), v.end(),cmp);
    string s;
    for (auto i : v)s += i;
    cout << get_sh(s) << endl;
    return 0;
}

ending

Adjacent term exchange method is also a common greedy method , Similar topics include Algorithm improvement Minimum string and New king game - subject - Daimayuan Online Judge