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
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>

#include "kollib.h"
#include "message.h"

using namespace std;

typedef vector<int> VI;
typedef long long LL;
typedef pair<int, int> PII;

#define FOR(x, b, e) for (int x = b; x <= (e); ++x)
#define FORD(x, b, e) for (int x = b; x >= (e); --x)
#define REP(x, n) for (int x = 0; x < (n); ++x)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int) (x).size())
#define FOREACH(i, c) for (VAR(i, (c).begin()); i != (c).end(); ++i)
#define PB push_back
#define ST first
#define ND second
#define MP make_pair

#define INF 1000000001

using namespace std;

vector<PII> V;
int K, N, n; // K - uczniowie, N - węzły, n - id węzła

int kp, Q;

void CollectStudents()
{
    int p, c;
    int dir = (N > 1 && n >= N / 2 ? -1 : 1);
    //fprintf(stderr, "CollectStudents node #%d dir = %d\n", n, dir);

    if (n == 0) {
        p = FirstNeighbor(1);
        c = 1;

        if (N > 1) {
            PutInt(N - 1, c);
            PutInt(N - 1, p);
            Send(N - 1);
        }
    } else {
        int r_id = (n - dir) % N;
        //fprintf(stderr, "CollectStudents node #%d waiting for msg from #%d\n", n, r_id);

        Receive(r_id);
        p = GetInt(r_id);
        c = GetInt(r_id);
        //fprintf(stderr, "CollectStudents node #%d p = %d c = %d\n", n, p, c);
    }

    int beg = n * kp;
    int end = min((n + 1) * kp, K) - 1;

    //fprintf(stderr, "CollectStudents resize vec to %d\n", end - beg + 1);
    if (beg <= end) {
        V.resize(end - beg + 1);
        if (dir == -1) swap(beg, end);

        for (int i = beg; i != end + dir; i += dir) {
            //fprintf(stderr, "CollectStudents i = %d p = %d c = %d\n", i, p, c);
            V[i - n * kp] = MP(c, i);
            int nx = SecondNeighbor(c);
            if (nx == p) nx = FirstNeighbor(c);
            p = c;
            c = nx;
        }
    }

    int s_id = (n + dir) % N;
    if (dir == 1 && s_id < N / 2 || dir == -1 && s_id >= N / 2) {
        //fprintf(stderr, "CollectStudents node #%d sending msg to #%d\n", n, s_id);
        PutInt(s_id, p);
        PutInt(s_id, c);
        Send(s_id);
    }

    sort(ALL(V));
    //REP(i, SIZE(V))
    //    fprintf(stderr, "CollectStudents i = %d: (%d, %d)\n", i, V[i].ST, V[i].ND);
}

void ProcessQueries()
{
    REP(i, Q) {
        int q[2] = { QueryFrom(i + 1),  QueryTo(i + 1) };
        REP(k, 2) {
            auto it = lower_bound(ALL(V), MP(q[k], -1));
            if (it != V.end() && it->ST == q[k]) {
                PutInt(0, i);
                PutInt(0, k);
                PutInt(0, it->ND);
                Send(0);
            }
        }
    }
}

void GatherResults()
{
    VI r[2];
    r[0].resize(Q, -1);
    r[1].resize(Q, -1);

    REP(i, 2 * Q) {
        int s = Receive(-1);
        int q = GetInt(s);
        int k = GetInt(s);
        int t = GetInt(s);

        r[k][q] = t;
    }

    REP(i, Q) {
        //fprintf(stderr, "Query #%d: %d %d\n", i, r[0][i], r[1][i]);
        int d = abs(r[0][i] - r[1][i]);
        printf("%d\n", min(d, K - d));
    }
}

int main() {
    K = NumberOfStudents();
    N = NumberOfNodes();
    n = MyNodeId();
    Q = NumberOfQueries();

    kp = (K + N - 1) / N;

    CollectStudents();
    ProcessQueries();

    if (n == 0) GatherResults();

    return 0;
}