Submission #339391

#	Time	Username	Problem	Language	Result	Execution time	Memory
339391		AmineWeslati	Miners (IOI07_miners)	C++14	100 / 100	111 ms	1196 KiB

miners

//Never stop trying
/*#pragma GCC target ("avx2")
#pragma GCC optimize ("Ofast")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")*/
#include "bits/stdc++.h"
using namespace std;
#define boost ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)

typedef long long ll;
typedef string str;
typedef double db;
typedef long double ld;
typedef pair<int, int> pi;
#define fi first
#define se second
typedef vector<int> vi;
typedef vector<pi> vpi;
typedef vector<str> vs;
typedef vector<ld> vd;
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define endl "\n"

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)

const int MOD = 1e9 + 7; //998244353
const ll INF = 2e9;
const int MX = 2e5 + 10;
const int nx[4] = {0, 0, 1, -1}, ny[4] = {1, -1, 0, 0}; //right left down up

template<class T> using V = vector<T>;
template<class T> bool ckmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); } // divide a by b rounded up
//constexpr int log2(int x) { return 31 - __builtin_clz(x); } // floor(log2(x))

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
//mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());

ll random(ll a, ll b){
    return a + rng() % (b - a + 1);
}

#ifndef LOCAL  
#define cerr if(false) cerr
#endif
#define dbg(x) cerr << #x << " : " << x << endl; 
#define dbgs(x,y) cerr << #x << " : " << x << " / " << #y << " : " << y << endl;
#define dbgv(v) cerr << #v << " : " << "[ "; for(auto it : v) cerr << it << ' '; cerr << ']' << endl;
#define here() cerr << "here" << endl;

void IO() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
}

int N; 
vi a;

int cnvrt(vi v){
	vi cnt(4,0);
	for(auto x: v) cnt[x]++;
	int ans=0;
	FOR(i,1,4) if(cnt[i]) ans++;
	return ans;
}

int main() {
    boost; IO();

    str s;
    cin>>N>>s;
    for(auto x: s){
    	if(x=='M') a.pb(1);
    	else if(x=='F') a.pb(2);
    	else a.pb(3);
    }

    int v[4][4][4];
    FOR(i,0,4) FOR(j,0,4) FOR(k,0,4) v[i][j][k]=cnvrt(vi{i,j,k});

    int dp[4][4][4][4];
    FOR(j,0,4) FOR(k,0,4) FOR(l,0,4) FOR(m,0,4) dp[j][k][l][m]=-INF;
    dp[0][0][0][0]=0;
    int ans=0;
    FOR(i,0,N){
    	int nw[4][4][4][4]; 
    	FOR(j,0,4) FOR(k,0,4) FOR(l,0,4) FOR(m,0,4) nw[j][k][l][m]=-INF;
    	FOR(j,0,4) FOR(k,0,4){
    		if(k && !j) break;
    		FOR(l,0,4) FOR(m,0,4){
    			if(m && !l) break;
    			int n=a[i];
	    		ckmax(nw[n][j][l][m],dp[j][k][l][m]+v[k][j][n]);
	    		ckmax(nw[j][k][n][l],dp[j][k][l][m]+v[m][l][n]);
    		}
		}
    	FOR(j,0,4) FOR(k,0,4) FOR(l,0,4) FOR(m,0,4){
    		dp[j][k][l][m]=nw[j][k][l][m];
    		ckmax(ans,dp[j][k][l][m]);
		}
    }
    cout << ans << endl;

    

    return 0;
}

/* Careful!!!
    .Array bounds
    .Infinite loops
    .Uninitialized variables / empty containers
    .Multisets are shit

   Some insights:
    .Binary search
    .Graph representation
    .Write brute force code
    .Change your approach
*/

• Subtask 1: 9 / 9
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 9 / 9
• Subtask 5: 9 / 9
• Subtask 6: 7 / 7
• Subtask 7: 8 / 8
• Subtask 8: 8 / 8
• Subtask 9: 8 / 8
• Subtask 10: 8 / 8
• Subtask 11: 8 / 8
• Subtask 12: 8 / 8