105 lines
3.8 KiB
C++
105 lines
3.8 KiB
C++
#include<bits/stdc++.h>
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using namespace std;
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// Short forms
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#define int long long
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#define ll long long
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#define endl '\n'
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#define ff first
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#define ss second
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#define pb push_back
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#define all(x) x.begin(), x.end()
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#define sz(x) (int)(x).size()
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// Outputs
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#define yes cout<<"YES"<<endl
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#define no cout<<"NO"<<endl
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// Constants
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#define PI 3.141592653589793238
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#define INF LONG_LONG_MAX
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#define MOD 1e9+7
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// Faster Input Output
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#define FAST_IO (ios_base:: sync_with_stdio(false),cin.tie(NULL));
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// Maths
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ll fact(ll n) { if(n==0) return 1; ll res = 1; for (ll i = 2; i <= n; i++) res = res * i; return res; }
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ll nPr(ll n, ll r) { return fact(n) / fact(n - r); }
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ll nCr(ll n, ll r) { return fact(n) / (fact(r) * fact(n - r)); }
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ll gcd(ll a, ll b) { if (b == 0) return a; return gcd(b, a % b); }
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ll lcm(ll a, ll b) { return (a * b) / gcd(a, b);}
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ll mypow(ll a, ll b) { ll ans = 1; while(b){ if (b&1) ans = (ans*a) ; b /= 2; a = (a*a); } return ans; }
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bool isPrime(ll n) { if(n <= 1) return false; for(ll i = 2; i <= sqrt(n); i++) if(n % i == 0) return false; return true; }
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//Debugging
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#ifndef ONLINE_JUDGE
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#define dbg(x) cerr << #x <<" "; _print(x); cerr << endl;
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#define dbgin(x) cerr << #x <<" "; _print(x); cerr << ";"<<endl;
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#else
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#define dbg(x)
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#define dbgin(x)
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#endif
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void _print(int t) {cerr << t;}void _print(string t) {cerr << t;}void _print(char t) {cerr << t;}
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void _print(long double t) {cerr << t;}void _print(double t) {cerr << t;}void _print(unsigned ll t) {cerr << t;}
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template <class T, class V> void _print(pair <T, V> p);
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template <class T> void _print(vector <T> v);template <class T> void _print(set <T> v);
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template <class T, class V> void _print(map <T, V> v);template <class T> void _print(multiset <T> v);
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template <class T, class V> void _print(pair <T, V> p) {cerr << "{"; _print(p.first); cerr << ","; _print(p.second); cerr << "}";}
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template <class T> void _print(vector <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
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template <class T> void _print(set <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
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template <class T> void _print(multiset <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
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template <class T> void _print(unordered_set <T> v) {cerr<<"[ "; for(T i : v) {_print(i); cerr<<" ";} cerr<<"]";}
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template <class T, class V> void _print(map <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}
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template <class T, class V> void _print(multimap <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}
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template <class T, class V> void _print(unordered_map <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}
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/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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bool cmp(pair<char,int>a, pair<char,int>b)
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{
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if(a.ff==b.ff)
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return a.ss<b.ss;
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return a.ff>b.ff;
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}
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void solve()
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{
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int n;
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string s;
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cin>>n>>s;
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vector<int>v;
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for(int i=0; i<sz(s); ++i)
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{
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while(!v.empty() && s[v.back()]<s[i])
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v.pop_back();
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v.pb(i);
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}
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int ct=count(all(s),s[v[0]]);
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for(int i=0; i<sz(v)/2; ++i)
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{
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swap(s[v[i]],s[v[sz(v)-i-1]]);
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}
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int sorted=1;
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for(int i=1;i<sz(s);++i)
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{
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if(s[i]<s[i-1])
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{
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sorted=0;
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break;
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}
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}
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if(sorted)
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cout<<sz(v)-ct<<endl;
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else
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cout<<-1<<endl;
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}
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int32_t main()
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{
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FAST_IO;
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int TC = 1;
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cin >> TC;
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while (TC--) solve();
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} |