#include<bits/stdc++.h> using namespace std; #define ll long long #define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; i++) #define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; i--) #define pa pair<ll, ll> #define fi first #define se second #define bit(mask, j) ((mask >> j) & 1) const ll mod = 1e9 + 7; const ll INF = 1e18; //-------------------------------------------------------------------- ll n; string T = "RGY"; string s; const ll N = 402; ll f[N][N][4][4]; ll dp(ll i, ll j, ll type, ll type2) { assert(j != 0); if(i == n) return j == 1 ? 0 : INF; if(f[i][j][type][type2] != -1) return f[i][j][type][type2]; ll type_new = T.find(s[i]); if(type_new == type) { return f[i][j][type][type2] = dp(i + 1, j + 1, type, type2); } ll res = INF; if(type != 3 && type2 != type_new) { res = min(res, dp(i + 1, j, type, type_new) + j); } if(j == 1) { res = min(res, dp(i + 1, j, type_new, type)); } else if(j >= 2) { res = min(res, dp(i + 1, j - 1, type, type_new) + j - 1); } return f[i][j][type][type2] = res; } void hbmt() { cin >> n; cin >> s; memset(f, -1, sizeof f); ll val = dp(0, 1, 3, 3); if(val == INF) cout << -1; else cout << val; } int main() { ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0); #define NAME "hbmt" if(fopen(NAME".inp", "r")) { freopen(NAME".inp", "r", stdin); freopen(NAME".out", "w", stdout); } //int t;cin>>t;while(t--) hbmt(); return 0; }

joi2019_ho_t3.cpp: In function 'int main()':
joi2019_ho_t3.cpp:56:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |                 freopen(NAME".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
joi2019_ho_t3.cpp:57:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |                 freopen(NAME".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~