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Submission #597587

# Submission time Handle Problem Language Result Execution time Memory
597587 2022-07-16T11:02:39 Z boris_mihov Event Hopping (BOI22_events) C++14
55 / 100
 123 ms 18984 KB 
#include <algorithm>
#include <iostream>
#include <numeric>

const int MAXN = 100000 + 10;
const int MAXLOG = 17;
const int INF = 1e9 + 10;

struct Event
{
    int s, e;
    inline friend bool operator < (Event a, Event b)
    {
        return a.s < b.s || (a.s == b.s && a.e < b.e);
    }
} ev[MAXN];

int n, q;
int getLog[MAXN];
int rmq[MAXLOG][MAXN];
int lift[MAXLOG][MAXN];
int perm[MAXN], newNum[MAXN];

int cmp(int x, int y)
{
    if (ev[x].e >= ev[y].e) return x;
    return y;
}

void buildRMQ()
{
    std::iota(rmq[0]+1, rmq[0]+1+n, 1);
    for (int log = 1 ; (1 << log) <= n ; ++log)
    {
        for (int i = 1 ; i + (1 << log) - 1 <= n ; ++i)
        {
            rmq[log][i] = cmp(rmq[log-1][i], rmq[log-1][i + (1 << log-1)]);
        }
    }

    for (int i = 1 ; i <= n ; ++i)
    {
        getLog[i] = getLog[i-1];
        if ((1 << getLog[i]+1) < i) ++getLog[i];
    }
}

int upperBinSearch(int value)
{
    int l = 0, r = n+1, mid;
    while (l < r - 1)
    {
        mid = (l + r) / 2;
        if (ev[mid].s <= value) l = mid;
        else r = mid;
    }

    return l;
}

int lowerBinSearch(int idx)
{
    int l = 0, r = n, mid;
    while (l < r - 1)
    {
        mid = (l + r) / 2;
        if (mid <= idx || ev[mid].s < ev[idx].s) l = mid;
        else r = mid;
    }

    return r;
}

int findMaximum(int l, int r)
{
    int log = getLog[r-l+1];
    return cmp(rmq[log][l], rmq[log][r - (1 << log) + 1]);
}

void buildLift()
{
    for (int log = 1 ; (1 << log) <= n ; ++log)
    {
        for (int i = 1 ; i <= n ; ++i)
        {
            lift[log][i] = lift[log-1][lift[log-1][i]];
        }
    }
}

int binaryLifting(int from, int value)
{
    if (ev[from].s > value) return -1;
    int ans = 1 + (ev[from].e < value);
    for (int log = MAXLOG-1 ; log >= 0 ; --log)
    {
        if (lift[log][from] == 0) continue;
        if (ev[lift[log][from]].e < value)
        {
            ans += (1 << log);
            from = lift[log][from];   
        }
    }

    if (ev[lift[0][from]].e < value) return -1;
    else return ans;
}

void solve()
{
    std::iota(perm+1, perm+1+n, 1);
    std::sort(perm+1, perm+1+n, [&](int x, int y)
    {
        return ev[x] < ev[y];
    });

    for (int i = 1 ; i <= n ; ++i)
    {
        newNum[perm[i]] = i;
    }

    std::sort(ev+1, ev+1+n);
    buildRMQ();

    for (int i = 1 ; i <= n ; ++i)
    {
        int from = lowerBinSearch(i);
        int to = upperBinSearch(ev[i].e);
        if (i+1 <= from && from <= to)
        {
            int jump = findMaximum(from, to);
            lift[0][i] = jump;
            if (i == jump) lift[0][i] = 0;
        }
    }

    buildLift();
    for (int i = 1 ; i <= q ; ++i)
    {
        int st, en;
        std::cin >> st >> en; 
        std::swap(st, en);
       
        if (st == en)
        {
            std::cout << 0 << '\n';
            continue;
        }

        st = newNum[st];
        en = ev[newNum[en]].s;
        int res = binaryLifting(st, en);
        if (res == -1) std::cout << "impossible\n";
        else std::cout << res << '\n';
    }
}

void read()
{
    std::cin >> n >> q;
    for (int i = 1 ; i <= n ; ++i)
    {
        std::cin >> ev[i].s >> ev[i].e;
        ev[i].s = INF - ev[i].s;
        ev[i].e = INF - ev[i].e;
        std::swap(ev[i].s, ev[i].e);
    }
}

void fastIO()
{
    std::ios_base :: sync_with_stdio(0);
    std::cout.tie(nullptr);
    std::cin.tie(nullptr);
}

int main()
{
    fastIO();
    read();
    solve();

    return 0;
}

Compilation message

events.cpp: In function 'void buildRMQ()':
events.cpp:37:70: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   37 |             rmq[log][i] = cmp(rmq[log-1][i], rmq[log-1][i + (1 << log-1)]);
      |                                                                   ~~~^~
events.cpp:44:28: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   44 |         if ((1 << getLog[i]+1) < i) ++getLog[i];
      |                   ~~~~~~~~~^~

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 89 ms 18456 KB Output is correct
3 Correct 83 ms 18620 KB Output is correct
4 Correct 89 ms 18512 KB Output is correct
5 Correct 98 ms 18660 KB Output is correct
6 Correct 105 ms 18648 KB Output is correct
7 Correct 82 ms 18768 KB Output is correct
8 Correct 74 ms 18752 KB Output is correct
9 Correct 87 ms 18556 KB Output is correct
10 Correct 113 ms 18948 KB Output is correct
11 Correct 99 ms 18984 KB Output is correct
12 Correct 65 ms 17672 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Correct 2 ms 484 KB Output is correct
5 Correct 1 ms 528 KB Output is correct
6 Correct 1 ms 476 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 472 KB Output is correct

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Correct 2 ms 484 KB Output is correct
5 Correct 1 ms 528 KB Output is correct
6 Correct 1 ms 476 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 472 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 1 ms 480 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 1 ms 532 KB Output is correct
15 Correct 1 ms 468 KB Output is correct
16 Correct 1 ms 484 KB Output is correct
17 Correct 1 ms 480 KB Output is correct
18 Correct 1 ms 468 KB Output is correct
19 Correct 32 ms 2348 KB Output is correct
20 Correct 36 ms 2420 KB Output is correct
21 Correct 30 ms 2724 KB Output is correct
22 Incorrect 25 ms 2796 KB Output isn't correct
23 Halted 0 ms 0 KB -

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Correct 2 ms 484 KB Output is correct
5 Correct 1 ms 528 KB Output is correct
6 Correct 1 ms 476 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 472 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 1 ms 468 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 1 ms 468 KB Output is correct
15 Correct 2 ms 468 KB Output is correct
16 Correct 1 ms 468 KB Output is correct
17 Correct 1 ms 476 KB Output is correct
18 Correct 1 ms 464 KB Output is correct
19 Correct 56 ms 16588 KB Output is correct
20 Correct 50 ms 16124 KB Output is correct
21 Correct 62 ms 16632 KB Output is correct
22 Correct 65 ms 16568 KB Output is correct
23 Correct 66 ms 16520 KB Output is correct
24 Correct 56 ms 16712 KB Output is correct
25 Correct 38 ms 16240 KB Output is correct

Subtask #5
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 78 ms 18420 KB Output is correct
2 Correct 79 ms 18476 KB Output is correct
3 Correct 94 ms 18404 KB Output is correct
4 Correct 79 ms 18552 KB Output is correct
5 Correct 111 ms 18820 KB Output is correct
6 Correct 123 ms 18448 KB Output is correct
7 Correct 114 ms 18636 KB Output is correct
8 Correct 95 ms 18880 KB Output is correct
9 Correct 54 ms 16872 KB Output is correct
10 Correct 87 ms 18340 KB Output is correct
11 Correct 89 ms 18040 KB Output is correct
12 Correct 83 ms 18252 KB Output is correct

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 89 ms 18456 KB Output is correct
3 Correct 83 ms 18620 KB Output is correct
4 Correct 89 ms 18512 KB Output is correct
5 Correct 98 ms 18660 KB Output is correct
6 Correct 105 ms 18648 KB Output is correct
7 Correct 82 ms 18768 KB Output is correct
8 Correct 74 ms 18752 KB Output is correct
9 Correct 87 ms 18556 KB Output is correct
10 Correct 113 ms 18948 KB Output is correct
11 Correct 99 ms 18984 KB Output is correct
12 Correct 65 ms 17672 KB Output is correct
13 Correct 0 ms 340 KB Output is correct
14 Correct 0 ms 340 KB Output is correct
15 Correct 1 ms 468 KB Output is correct
16 Correct 2 ms 484 KB Output is correct
17 Correct 1 ms 528 KB Output is correct
18 Correct 1 ms 476 KB Output is correct
19 Correct 1 ms 468 KB Output is correct
20 Correct 1 ms 468 KB Output is correct
21 Correct 1 ms 472 KB Output is correct
22 Correct 0 ms 340 KB Output is correct
23 Correct 0 ms 340 KB Output is correct
24 Correct 1 ms 480 KB Output is correct
25 Correct 1 ms 468 KB Output is correct
26 Correct 1 ms 532 KB Output is correct
27 Correct 1 ms 468 KB Output is correct
28 Correct 1 ms 484 KB Output is correct
29 Correct 1 ms 480 KB Output is correct
30 Correct 1 ms 468 KB Output is correct
31 Correct 32 ms 2348 KB Output is correct
32 Correct 36 ms 2420 KB Output is correct
33 Correct 30 ms 2724 KB Output is correct
34 Incorrect 25 ms 2796 KB Output isn't correct
35 Halted 0 ms 0 KB -