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Submission #1055501

# Submission time Handle Problem Language Result Execution time Memory
1055501 2024-08-12T20:15:09 Z MilosMilutinovic Islands (IOI08_islands) C++17
90 / 100
 429 ms 131072 KB 
#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 1000000;
 
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;
  while (!g[v].empty()) {
    int u = g[v].back();
    g[v].pop_back();
    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]);
  }
  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;
  }
  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];
    }
    long long c = 0;
    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]]);
    }
    long long t = d[cyc[sz - 1]] + l[cyc[sz - 1]];
    int low, high, pos, mid;
    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 8 ms 23900 KB Output is correct
2 Correct 11 ms 23900 KB Output is correct
3 Correct 8 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 23856 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 23896 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 23900 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 23896 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 12 ms 24668 KB Output is correct
2 Correct 19 ms 25964 KB Output is correct
3 Correct 12 ms 25180 KB Output is correct
4 Correct 9 ms 24412 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 26904 KB Output is correct
2 Correct 24 ms 29268 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 43 ms 34784 KB Output is correct
2 Correct 53 ms 37440 KB Output is correct
3 Correct 56 ms 38752 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 75 ms 44564 KB Output is correct
2 Correct 89 ms 50256 KB Output is correct
3 Correct 122 ms 58656 KB Output is correct
4 Correct 130 ms 62068 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 129 ms 55860 KB Output is correct
2 Correct 300 ms 75496 KB Output is correct
3 Correct 137 ms 62892 KB Output is correct
4 Correct 177 ms 76628 KB Output is correct
5 Correct 182 ms 74832 KB Output is correct
6 Correct 429 ms 76548 KB Output is correct
7 Correct 194 ms 82516 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 172 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -