Submission #1540659

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,k,n) for(int i = (int)(k); i < (int)(n); i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(a) a.begin(), a.end()
#define MS(m,v) memset(m,v,sizeof(m))
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int, int> pii;
const int MOD = 1e9 + 7;
template<class T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<class T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<class T>
istream& operator >> (istream& is, vector<T>& v)
{
	for (auto &i : v) is >> i;
	return is;
}
template<class T>
ostream& operator<<(ostream& os, vector<T>& v)
{
	const string delimiter = "\n";
	REP(i, v.size())
	{
		os << v[i];
		if (i != v.size() - 1) os << delimiter;
	}
	return os;
}
/*--------------------template--------------------*/

int main()
{
	cin.sync_with_stdio(false); cout << fixed << setprecision(10);
	string s; cin >> s;
	ll n = s.size();
	vi cnt(26);
	for (auto c : s) cnt[c - 'a']++;
	ll ans = n * (n - 1) / 2 + 1;
	for (ll i : cnt)
	{
		if (i > 0) ans -= i * (i - 1) / 2;
	}
	cout << ans << endl;
	return 0;
}

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