Submission #503794

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
503794	2022-01-08T22:52:01 Z	tabr	Islands (IOI08_islands)	C++17	80 / 100	771 ms	131072 KB

islands

#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

const int N = (int) 1e6;
int p[N];

int dsu_get(int x) {
    if (p[x] == x) {
        return x;
    } else {
        return p[x] = dsu_get(p[x]);
    }
}

bool dsu_unite(int x, int y) {
    x = dsu_get(x);
    y = dsu_get(y);
    if (x == y) {
        return false;
    }
    p[x] = y;
    return true;
}

int l[N];
int nxt[N];
long long dist[N];
long long max_dist[N];
bool cycle[N];
bool was[N];
vector<int> g[N];
pair<int, long long> deq[N];
int x[N];
int order[N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    iota(p, p + n, 0);
    for (int i = 0; i < n; i++) {
        int j;
        cin >> j >> l[i];
        j--;
        g[j].emplace_back(i);
        dsu_unite(i, j);
        nxt[i] = j;
    }
    long long ans = 0;
    for (int i = 0; i < n; i++) {
        if (i != dsu_get(i)) {
            continue;
        }
        int c = i;
        while (!was[c]) {
            was[c] = 1;
            c = nxt[c];
        }
        int u = nxt[c];
        cycle[c] = 1;
        int sz = 1;
        x[0] = c;
        while (u != c) {
            cycle[u] = 1;
            x[sz++] = u;
            u = nxt[u];
        }
        int sz2 = 0;
        int beg = 0;
        int end = 0;
        for (int jj = 0; jj < sz; jj++) {
            int j = x[jj];
            deq[end++].first = j;
            while (beg < end) {
                int v = deq[beg++].first;
                order[sz2++] = v;
                for (int to : g[v]) {
                    if (cycle[to]) {
                        continue;
                    }
                    dist[to] = dist[v] + l[to];
                    deq[end++].first = to;
                }
            }
        }
        long long t = 0;
        for (int j = sz2 - 1; j >= 0; j--) {
            int v = order[j];
            max_dist[v] = max(max_dist[v], dist[v]);
            if (cycle[v]) {
                continue;
            }
            int to = nxt[v];
            t = max(t, max_dist[to] + max_dist[v] - dist[to] * 2);
            max_dist[to] = max(max_dist[to], max_dist[v]);
        }
        long long y = l[c];
        beg = end = 0;
        deq[end++] = make_pair(0, 0);
        for (int jj = 1; jj < sz * 2; jj++) {
            int j = jj % sz;
            if (x[deq[beg].first] == x[j]) {
                beg++;
            }
            t = max(t, y + max_dist[x[j]] - deq[beg].second);
            long long z = y - max_dist[x[j]];
            while (beg < end && deq[end - 1].second >= z) {
                end--;
            }
            y += l[x[j]];
            deq[end++] = make_pair(j, z);
        }
        ans += t;
    }
    cout << ans << '\n';
    return 0;
}

Subtask #1
33.0 / 33.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	23912 KB	Output is correct
2	Correct	12 ms	23780 KB	Output is correct
3	Correct	15 ms	23884 KB	Output is correct
4	Correct	12 ms	23780 KB	Output is correct
5	Correct	14 ms	23756 KB	Output is correct
6	Correct	12 ms	23756 KB	Output is correct
7	Correct	16 ms	23768 KB	Output is correct
8	Correct	16 ms	23756 KB	Output is correct
9	Correct	12 ms	23776 KB	Output is correct
10	Correct	11 ms	23756 KB	Output is correct
11	Correct	11 ms	23876 KB	Output is correct

Subtask #2
3.0 / 3.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	12 ms	23944 KB	Output is correct
2	Correct	12 ms	23944 KB	Output is correct

Subtask #3
4.0 / 4.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	11 ms	23904 KB	Output is correct
2	Correct	12 ms	24100 KB	Output is correct

Subtask #4
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	18 ms	24656 KB	Output is correct
2	Correct	24 ms	26060 KB	Output is correct
3	Correct	19 ms	25200 KB	Output is correct
4	Correct	15 ms	24560 KB	Output is correct

Subtask #5
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	26 ms	27072 KB	Output is correct
2	Correct	37 ms	29312 KB	Output is correct

Subtask #6
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	66 ms	37168 KB	Output is correct
2	Correct	78 ms	39648 KB	Output is correct
3	Correct	81 ms	42096 KB	Output is correct

Subtask #7
10.0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	107 ms	44080 KB	Output is correct
2	Correct	149 ms	56904 KB	Output is correct
3	Correct	156 ms	65868 KB	Output is correct
4	Correct	180 ms	70772 KB	Output is correct

Subtask #8
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	221 ms	74756 KB	Output is correct
2	Correct	473 ms	85880 KB	Output is correct
3	Correct	203 ms	62068 KB	Output is correct
4	Correct	258 ms	82044 KB	Output is correct
5	Correct	259 ms	83564 KB	Output is correct
6	Correct	771 ms	84076 KB	Output is correct
7	Runtime error	364 ms	131072 KB	Execution killed with signal 11

Subtask #9
0 / 10.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	289 ms	114764 KB	Output is correct
2	Correct	281 ms	101972 KB	Output is correct
3	Runtime error	396 ms	131072 KB	Execution killed with signal 11
4	Halted	0 ms	0 KB	-

Submission #503794

Compilation message