#include<bits/stdc++.h> //#include "minesweeper.h" typedef int ll; #define fi first #define se second #define pii pair<ll,ll> #define N 500005 #define endl '\n' #define y0 Y0 using namespace std; const ll inf = 1e9; ll rand(ll l, ll r) { return l + rand() % (r - l + 1); } bool ghuy4g; ll f[100005][4][4][4][4]; ll n, a[N]; ll cal(ll x, ll y, ll z) { ll res = 0; if (x) res ++ ; if (y && y != x) res ++ ; if (z && z != y && z != x) res ++ ; return res; } void mx(ll &u, ll v) { u = max(u, v); } void solve() { for (int i = 0; i <= n; i ++) { for (int j = 0; j <= 3; j ++) { for (int z = 0; z <= 3; z ++) { for (int u = 0; u <= 3; u ++) { for (int v = 0; v <= 3; v ++) { f[i][j][z][u][v] = -inf; } } } } } f[0][0][0][0][0] = 0; ll ans = 0; for (int i = 1; i <= n; i ++) { for (int x1 = 0; x1 <= 3; x1 ++) { for (int x2 = 0; x2 <= 3; x2 ++) { for (int u1 = 0; u1 <= 3; u1 ++) { for (int u2 = 0; u2 <= 3; u2 ++) { if (f[i - 1][x1][x2][u1][u2] == -inf) continue; // dien vao 1 ll base = f[i - 1][x1][x2][u1][u2]; mx(f[i][a[i]][x1][u1][u2], base + cal(x1, x2, a[i])); mx(f[i][x1][x2][a[i]][u1], base + cal(u1, u2, a[i])); ans = max(ans, f[i][a[i]][x1][u1][u2]); ans = max(ans, f[i][x1][x2][a[i]][u1]); } } } } } cout << ans << endl; } bool klinh; signed main() { if (fopen("kghmdlod.inp", "r")) { freopen("kghmdlod.inp", "r", stdin); freopen("kghmdlod.out", "w", stdout); } srand(time(0)); ios_base::sync_with_stdio(0); cin.tie(0); cin >> n; //n = 1e5; for (int i = 1; i <= n; i ++) { char u; cin >> u; if (u == 'M') a[i] = 1; if (u == 'B') a[i] = 2; if (u == 'F') a[i] = 3; //a[i] = rand(1, 3); } solve(); cerr << fabs(&klinh - &ghuy4g) / double(1024 * 1024); }

miners.cpp: In function 'int main()':
miners.cpp:74:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |                 freopen("kghmdlod.inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
miners.cpp:75:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |                 freopen("kghmdlod.out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~