Submission #69702

#	Time	Username	Problem	Language	Result	Execution time	Memory
69702		3zp	Homecoming (BOI18_homecoming)	C++14	0 / 100	40 ms	8576 KiB

homecoming

#include<bits/stdc++.h>
#include "homecoming.h"
using namespace std;
long long sa[60009], sb[60009];
long long su (long long l, long long r){
    if(!l) return -sb[r]+sa[r];
    return -sb[r] + sa[r] + sb[l-1] - sa[l-1];
}
long long Sb(long long l, long long r){
    if(!l) return sb[r];
    else return sb[r] - sb[l-1];
}
long long M[5009][22];
long long dp[40009][2];
int A1[2000009];
int B1[2000009];
long long int solve(int N, int K, int *A, int *B){
    if(N > 1e5) return 1/0;
    for(long long i = 0; i < N; i++)
        A1[i] = A[i],
        B1[i] = B[i];
    for(long long i = 0; i < 2*N; i++)
        A1[i+N] = A1[i],
        B1[i+N] = B1[i];
    sa[0] = A1[0];
    sb[0] = B1[0];

    for(long long i = 1; i < 3*N; i++)
        sa[i] = sa[i-1] + A1[i],
        sb[i] = sb[i-1] + B1[i];
    for(int i = 0 ;i < 2*N; i++)
        M[i][0] = su(i,i);
    for(long long i = 1; (1 << i) < 2*N; i++){
        for(long long j = 0; j + (1<<i) - 1 < 2*N; j++){
            long long m1 = M[j][i-1];
            long long m2 = M[j+(1<<(i-1))][i-1];
            M[j][i] = max(m2, m1 + su(j+(1<<i-1), j+(1<<i) - 1));
        }
    }
    long long masof = 1e9, FI = -1;
    for(long long i = N; i < 2*N; i++){
        long long S = A1[i] - sb[i+K-1] + sb[i-1];
        long long x = i, ss = 0;
        for(long long L = 21; L >= 0; L--){
            if(x - (1<<L) < 0)  continue;
            if(M[x - (1<<L)][L] + ss + S >= 0) continue;
            ss += su(x - (1 << L), x -1);
            x = x - (1 << L);
        }
        int l;
        if(S >= 0) l = i;

        else l = x - 1;
        if(l <= i - N) l = -1;
        if(l != -1 && masof > i - l) {
            FI = i;
            masof = i - l;
        }
      //  cout << i <<" "<<l << " "<<S<<" "<<A1[i]<<" "<<sb[i+K-1]<<" "<<sb[i-1]<<endl;
    }
   // cout <<FI << endl;
    if(FI == -1) return max((long long)0, sa[N-1] - sb[N-1]);
    FI -= N;
    dp[FI][0] = -1e18;
    dp[FI][1] = A1[FI] - Sb(FI, FI+K-1);
    for(long long i = FI + 1; i < FI + N - K; i++){
        dp[i][0] = max(dp[i-1][0] , dp[i-1][1]);
        dp[i][1] = dp[i-1][1] + A1[i] - B1[i + K - 1];
        if(i - K >= FI) dp[i][1] =max(dp[i][1], max(dp[i - K][0] , dp[i - K][1] +
                                                A1[i] - Sb(i, i+K-1)));
        //cout << i <<" "<<dp[i][0] <<" "<<dp[i][1]<<endl;
    }
    long long ans = max(dp[FI + N - K - 1][0], dp[FI+ N - K - 1][1]);
    long long s = 0;
    for(long long i =  FI - 1; i > FI - N + K; i --){
        s += A1[i+N] - B1[i+N];
        ans =max(ans, s + max(dp[i + N - K - 1][0], dp[i + N - K - 1][1]));
    }
    //cout <<sa[N-1]<<" "<<sb[N-1]<<endl;
    return max(max((long long)0,ans), sa[N-1]-sb[N-1]);
    return 0;
}

Compilation message (stderr)

homecoming.cpp: In function 'long long int solve(int, int, int*, int*)':
homecoming.cpp:18:25: warning: division by zero [-Wdiv-by-zero]
     if(N > 1e5) return 1/0;
                        ~^~
homecoming.cpp:37:46: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
             M[j][i] = max(m2, m1 + su(j+(1<<i-1), j+(1<<i) - 1));
                                             ~^~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 18
• Subtask 3: 0 / 31
• Subtask 4: 0 / 38