1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
#include <iostream>
#include <vector>
#include <algorithm>
#include "message.h"
#include "kanapka.h"

struct Chunk {
    Chunk(): max_pref(0), max_suf(0), sum(0), max_pref_suf_sum(0) {}
    Chunk(long long taste):
            max_pref(std::max(0LL, taste)),
            max_suf(std::max(0LL, taste)),
            sum(taste),
            max_pref_suf_sum(std::max(0LL, taste)) {}
    long long max_pref;
    long long max_suf;
    long long sum;
    long long max_pref_suf_sum;
};

void Send(int target, const Chunk& message) {
    PutLL(target, message.max_pref);
    PutLL(target, message.max_suf);
    PutLL(target, message.sum);
    PutLL(target, message.max_pref_suf_sum);
    Send(target);
}

Chunk ReceiveChunk(int source) {
    int real = Receive(source);
    Chunk rv;
    rv.max_pref = GetLL(real);
    rv.max_suf = GetLL(real);
    rv.sum = GetLL(real);
    rv.max_pref_suf_sum = GetLL(real);
    return rv;
}

std::ostream& operator<<(std::ostream& os, const Chunk& msg) {
    os << "Chunk(" << msg.max_pref << ", " << msg.max_suf << ", "
       << msg.sum << ", " << msg.max_pref_suf_sum << ")";
    return os;
}

int NODES;

Chunk operator+(const Chunk& chunk1, const Chunk& chunk2) {
    Chunk rv;
    rv.sum = chunk1.sum + chunk2.sum;
    rv.max_pref = std::max(chunk1.max_pref, chunk1.sum  + chunk2.max_pref);
    rv.max_suf = std::max(chunk2.max_suf, chunk2.sum  + chunk1.max_suf);
    rv.max_pref_suf_sum = std::max({chunk1.max_pref_suf_sum + chunk2.sum,
                                    chunk1.sum + chunk2.max_pref_suf_sum,
                                    chunk1.max_pref + chunk2.max_suf});
    return rv;
}

Chunk& operator+=(Chunk& chunk1, const Chunk& chunk2) {
    chunk1 = chunk1 + chunk2;
    return chunk1;
}


Chunk ComputeChunk() {
    Chunk rv;
    int start = static_cast<long long>(MyNodeId()) * GetN() / NODES;
    int end = static_cast<long long>(MyNodeId() + 1) * GetN() / NODES;
    for (int i = start; i < end; ++i) {
        rv += Chunk(GetTaste(i));
    }
    return rv;
}

const int kTastesAtOnce = 1000000;

int main() {
    NODES = std::min((long long) NumberOfNodes(), GetN());
//     std::cerr << "node " << MyNodeId() << " out of " << NODES << "\n";
    if (MyNodeId() >= NODES) {
        return 0;
    }
    if (MyNodeId() == 0) {
        Chunk result = ComputeChunk();
        for (int i = 1; i < NODES; ++i) {
            result += ReceiveChunk(i);
        }
        std::cout << result.max_pref_suf_sum << "\n";
    } else {
        Send(0, ComputeChunk());
    }
    return 0;
}