oj.uz

Submission #503815

# Submission time Handle Problem Language Result Execution time Memory
503815 2022-01-08T23:50:35 Z tabr Islands (IOI08_islands) C++17
80 / 100
 555 ms 67736 KB 
#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

const int N = (int) 1e6 + 100;
int g[N];
int deg[N + 1];
int p[N];
int l[N];
int nxt[N];
long long dist[N];
long long max_dist[N];
bool cycle[N];
bool was[N];
pair<int, long long> deq[N];
int order[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 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--;
        deg[j + 1]++;
        dsu_unite(i, j);
        nxt[i] = j;
    }
    for (int i = 0; i < n; i++) {
        deg[i + 1] += deg[i];
    }
    iota(g, g + n, 0);
    sort(g, g + n, [&](int x, int y) {
        if (nxt[x] == nxt[y]) {
            return x < y;
        }
        return nxt[x] < nxt[y];
    });
    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;
        while (u != c) {
            cycle[u] = 1;
            u = nxt[u];
            sz++;
        }
        int sz2 = 0;
        int beg = 0;
        int end = 0;
        int x = c;
        for (int jj = 0; jj < sz; jj++) {
            int j = x;
            x = nxt[x];
            deq[end++].first = j;
            while (beg < end) {
                int v = deq[beg++].first;
                order[sz2++] = v;
                for (int toid = deg[v]; toid < deg[v + 1]; toid++) {
                    int to = g[toid];
                    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);
        x = nxt[c];
        for (int jj = 1; jj < sz * 2; jj++) {
            int j = jj % sz;
            if (deq[beg].first == j) {
                beg++;
            }
            t = max(t, y + max_dist[x] - deq[beg].second);
            long long z = y - max_dist[x];
            while (beg < end && deq[end - 1].second >= z) {
                end--;
            }
            y += l[x];
            deq[end++] = make_pair(j, z);
            x = nxt[x];
        }
        ans += t;
    }
    cout << ans << '\n';
    return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 0 ms 332 KB Output is correct
4 Correct 0 ms 332 KB Output is correct
5 Correct 0 ms 332 KB Output is correct
6 Correct 0 ms 332 KB Output is correct
7 Correct 0 ms 332 KB Output is correct
8 Correct 0 ms 332 KB Output is correct
9 Correct 0 ms 332 KB Output is correct
10 Correct 0 ms 332 KB Output is correct
11 Correct 0 ms 332 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 488 KB Output is correct
2 Correct 2 ms 588 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 972 KB Output is correct
2 Correct 12 ms 2380 KB Output is correct
3 Correct 7 ms 1484 KB Output is correct
4 Correct 4 ms 844 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 3148 KB Output is correct
2 Correct 25 ms 4464 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 11636 KB Output is correct
2 Correct 57 ms 10816 KB Output is correct
3 Correct 63 ms 15280 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 81 ms 15132 KB Output is correct
2 Correct 109 ms 28684 KB Output is correct
3 Correct 139 ms 27808 KB Output is correct
4 Correct 146 ms 38596 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 232 ms 55032 KB Output is correct
2 Correct 344 ms 52256 KB Output is correct
3 Correct 165 ms 30028 KB Output is correct
4 Correct 216 ms 47332 KB Output is correct
5 Correct 217 ms 51132 KB Output is correct
6 Correct 555 ms 49084 KB Output is correct
7 Incorrect 227 ms 57028 KB Output isn't correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 235 ms 67736 KB Output is correct
2 Correct 230 ms 55196 KB Output is correct
3 Incorrect 317 ms 61740 KB Output isn't correct
4 Halted 0 ms 0 KB -