Submission #1090900

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090900		eltu0815	Chorus (JOI23_chorus)	C++14	87 / 100	7078 ms	36308 KiB

chorus

#include <bits/stdc++.h>
#define MAX 1000005
#define MOD (ll)(1048573)
#define INF (ll)(1e12)
#define inf (int)(1e9)
#define eps (double)(1e-8)
 
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
int tt, N, K;
string str;

int cnt[MAX], pos[MAX], can[MAX], q[MAX], k[MAX];
ll dp[MAX], sum[MAX];

#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

inline int readChar();
template<class T = int> inline T readInt();
template<class T> inline void writeInt(T x, char end = 0);
inline void writeChar(int x);
inline void writeWord(const char *s);
static const int buf_size = 1 << 18;
inline int getChar(){
    #ifndef LOCAL
    static char buf[buf_size];
    static int len = 0, pos = 0;
    if(pos == len) pos = 0, len = fread(buf, 1, buf_size, stdin);
    if(pos == len) return -1;
    return buf[pos++];
    #endif
}
inline int readChar(){
    #ifndef LOCAL
    int c = getChar();
    while(c <= 32) c = getChar();
    return c;
    #else
    char c; cin >> c; return c;
    #endif
}
template <class T>
inline T readInt(){
    #ifndef LOCAL
    int s = 1, c = readChar();
    T x = 0;
    if(c == '-') s = -1, c = getChar();
    while('0' <= c && c <= '9') x = x * 10 + c - '0', c = getChar();
    return s == 1 ? x : -x;
    #else
    T x; cin >> x; return x;
    #endif
}
static int write_pos = 0;
static char write_buf[buf_size];
inline void writeChar(int x){
    if(write_pos == buf_size) fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
    write_buf[write_pos++] = x;
}
template <class T>
inline void writeInt(T x, char end){
    if(x < 0) writeChar('-'), x = -x;
    char s[24]; int n = 0;
    while(x || !n) s[n++] = '0' + x % 10, x /= 10;
    while(n--) writeChar(s[n]);
    if(end) writeChar(end);
}
inline void writeWord(const char *s){
    while(*s) writeChar(*s++);
}
struct Flusher{
    ~Flusher(){ if(write_pos) fwrite(write_buf, 1, write_pos, stdout), write_pos = 0; }
}flusher;


ll cost(int i, int j) {
    return max(sum[j] - sum[pos[i - 1] - 1] - (ll)(j - pos[i - 1] + 1) * (i - 1), 0ll);
}

ll func(int i, int j) {
    return dp[i] + cost(i + 1, j);
}

int cross(int i, int j) {
    int lo = j , hi = N + 1;
    while(lo + 1 < hi) {
        int mid = (lo + hi) >> 1;
        if(func(i, mid) <= func(j, mid)) lo = mid;
        else hi = mid;
    }
    return lo; 
}

void monotoneQueue(ll lambda) {
    int str = 0, ed = 1;
    q[0] = 0; can[0] = N;
    for(int i = 1; i <= N; ++i) {
        while(can[str] < i) ++str;
        dp[i] = func(q[str], i) + lambda; k[i] = k[q[str]] + 1;
        
        while(str + 1 < ed && can[ed - 2] >= cross(q[ed - 1], i)) --ed;
        can[ed - 1] = cross(q[ed - 1], i); q[ed] = i; can[ed] = N;
        ++ed;
    }

    return;
}

ll alienTrick() {
    ll lo = -1, hi = INF;
    ll ans = 0;
    while(lo + 1 < hi) {
        ll mid = (lo + hi) >> 1;
        monotoneQueue(mid);
        
        ans = max(ans, dp[N] - mid * K);
        
        if(k[N] >= K) lo = mid;
        else hi = mid;
    }
    
    return ans;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    
    N = readInt();
    K = readInt();
    for(int i = 0; i < 2 * N; ++i) str += readChar();
    for(int i = 0, tmp = 0, p = 0; i < 2 * N; ++i) {
        if(str[i] == 'A') cnt[++p] = tmp;
        else ++tmp;
    }
    
    for(int i = 0, j = 1; i <= N; ++i) {
        while(j <= N && cnt[j] < i) ++j;
        pos[i] = max(i + 1, j);
    }
    
    for(int i = 1; i <= N; ++i) sum[i] = sum[i - 1] + cnt[i];
    
    writeInt(alienTrick(), ' ');
    return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 21 / 21
• Subtask 4: 26 / 26
• Subtask 5: 0 / 13