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Submission #1055511

# Submission time Handle Problem Language Result Execution time Memory
1055511 2024-08-12T20:34:59 Z MilosMilutinovic Islands (IOI08_islands) C++14
100 / 100
 359 ms 98004 KB 
#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 1000002;
 
int a[N], l[N], cyc[N];
 
long long d[N], dp[N], mx[N];
 
vector<int> g[N];
 
long long Solve(int v, int pv) {
  long long mx = 0;
  for (int u : g[v]) {
    if (d[u] != -2 || u == pv) {
      continue;
    }
    mx = max(mx, Solve(u, v));
    mx = max(mx, dp[v] + dp[u] + l[u]);
    dp[v] = max(dp[v], dp[u] + l[u]);
  }
  vector<int>().swap(g[v]);
  return mx;
}
 
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> l[i];
    --a[i];
  }
  for (int i = 0; i < n; i++) {
    g[a[i]].push_back(i);
  }
  long long res = 0;
  for (int i = 0; i < n; i++) {
    d[i] = -1;
  }
  long long c, t;
  int low, high, pos, mid;
  for (int i = 0; i < n; i++) {
    if (d[i] != -1) {
      continue;
    }
    int sz = 0;
    cyc[sz++] = i;
    d[i] = 0;
    for (int b = 0; b < sz; b++) {
      int x = cyc[b];
      if (d[a[x]] == -1) {
        d[a[x]] = 0;
        cyc[sz++] = a[x];
      }
      for (int y : g[x]) {
        if (d[y] == -1) {
          d[y] = 0;
          cyc[sz++] = y;
        }
      }
    }
    for (int x = 0; x < sz; x++) {
      d[cyc[x]] = -1;
    }
    int x = i;
    while (d[x] == -1) {
      d[x] = 0;
      x = a[x];
    }
    for (int x = 0; x < sz; x++) {
      d[cyc[x]] = -2;
    }
    sz = 0;
    cyc[sz++] = x;
    int y = a[x];
    while (y != x) {
      cyc[sz++] = y;
      y = a[y];
    }
    d[cyc[0]] = 0;
    for (int i = 1; i < sz; i++) {
      int x = cyc[i - 1], y = cyc[i];
      d[y] = d[x] + l[x];
    }
    int nsz = sz;
    for (int b = 0; b < nsz; b++) {
      int x = cyc[b];
      for (int y : g[x]) {
        if (d[y] == -2) {
          d[y] = -3;
          cyc[nsz++] = y;
        }
      }
    }
    c = 0;
    for (int b = nsz - 1; b >= 0; b--) {
      int x = cyc[b];
      for (int y : g[x]) {
        if (d[y] == -3 && a[y] == x) {
          c = max(c, dp[x] + dp[y] + l[y]);
          dp[x] = max(dp[x], dp[y] + l[y]);
        }
      }
    }
    for (int i = 0; i < sz; i++) {
      // c = max(c, Solve(cyc[i], cyc[i]));
      c = max(c, dp[cyc[i]]);
    }
    for (int i = sz - 1; i >= 0; i--) {
      if (i + 1 < sz) {
        mx[i] = mx[i + 1];
      } else {
        mx[i] = d[cyc[i]] + dp[cyc[i]];
      }
      mx[i] = max(mx[i], d[cyc[i]] + dp[cyc[i]]);
    }
    t = d[cyc[sz - 1]] + l[cyc[sz - 1]];
    for (int i = 0; i < sz; i++) {
      low = i + 1, high = sz - 1, pos = i;
      while (low <= high) {
        mid = (low + high) >> 1;
        if (t - (d[cyc[mid]] - d[cyc[i]]) >= (d[cyc[mid]] - d[cyc[i]])) {
          pos = mid;
          low = mid + 1;
        } else {
          high = mid - 1;
        }
      }
      if (pos + 1 < sz) {
        c = max(c, -d[cyc[i]] + dp[cyc[i]] + mx[pos + 1]);
      }
    }
    for (int i = sz - 1; i >= 0; i--) {
      if (i + 1 < sz) {
        mx[i] = mx[i + 1];
      } else {
        mx[i] = -d[cyc[i]] + dp[cyc[i]];
      }
      mx[i] = max(mx[i], -d[cyc[i]] + dp[cyc[i]]);
    }
    for (int i = 0; i < sz; i++) {
      low = i + 1, high = sz - 1, pos = i;
      while (low <= high) {
        mid = (low + high) >> 1;
        if (t - (d[cyc[mid]] - d[cyc[i]]) >= (d[cyc[mid]] - d[cyc[i]])) {
          pos = mid;
          low = mid + 1;
        } else {
          high = mid - 1;
        }
      }
      if (pos > i) {
        c = max(c, t + d[cyc[i]] + dp[cyc[i]] + mx[i + 1]);
      }
    }
    res += c;
  }
  cout << res << '\n';
  return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 23896 KB Output is correct
2 Correct 8 ms 23900 KB Output is correct
3 Correct 9 ms 23900 KB Output is correct
4 Correct 8 ms 23900 KB Output is correct
5 Correct 8 ms 23900 KB Output is correct
6 Correct 8 ms 23900 KB Output is correct
7 Correct 8 ms 23900 KB Output is correct
8 Correct 8 ms 23896 KB Output is correct
9 Correct 8 ms 23900 KB Output is correct
10 Correct 8 ms 23900 KB Output is correct
11 Correct 8 ms 23900 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 23900 KB Output is correct
2 Correct 8 ms 23968 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 23900 KB Output is correct
2 Correct 9 ms 24156 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 24668 KB Output is correct
2 Correct 15 ms 25800 KB Output is correct
3 Correct 13 ms 25192 KB Output is correct
4 Correct 15 ms 24412 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 26712 KB Output is correct
2 Correct 27 ms 29524 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 40 ms 35152 KB Output is correct
2 Correct 53 ms 38236 KB Output is correct
3 Correct 63 ms 39900 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 74 ms 46160 KB Output is correct
2 Correct 93 ms 52052 KB Output is correct
3 Correct 125 ms 60500 KB Output is correct
4 Correct 137 ms 64776 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 125 ms 59728 KB Output is correct
2 Correct 279 ms 79372 KB Output is correct
3 Correct 150 ms 65368 KB Output is correct
4 Correct 189 ms 79808 KB Output is correct
5 Correct 181 ms 77660 KB Output is correct
6 Correct 342 ms 79952 KB Output is correct
7 Correct 196 ms 86100 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 158 ms 98004 KB Output is correct
2 Correct 165 ms 97872 KB Output is correct
3 Correct 221 ms 97872 KB Output is correct
4 Correct 152 ms 85840 KB Output is correct
5 Correct 179 ms 81744 KB Output is correct
6 Correct 174 ms 84108 KB Output is correct
7 Correct 359 ms 83788 KB Output is correct