Submission #521114

#	Time	Username	Problem	Language	Result	Execution time	Memory
521114		Alex_tz307	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	100 / 100	500 ms	26324 KiB

skyscraper

#include <bits/stdc++.h>
#define INF 0x3f3f3f3f

using namespace std;

const int SQRT = 175;

void minSelf(int &x, int y) {
  if (y < x) {
    x = y;
  }
}

void testCase() {
  int n, m;
  cin >> n >> m;
  vector<vector<int>> g(n);
  int s = 0, t = 0;
  for (int i = 0; i < m; ++i) {
    int b, p;
    cin >> b >> p;
    if (0 <= b - p || b + p < n) {
      g[b].emplace_back(p);
    }
    if (i == 0) {
      s = b;
    }
    if (i == 1) {
      t = b;
    }
  }
  if (s == t) {
    cout << "0\n";
    return;
  }
  for (int v = 0; v < n; ++v) {
    sort(g[v].begin(), g[v].end());
    g[v].erase(unique(g[v].begin(), g[v].end()), g[v].end());
  }
  queue<pair<int, int>> q;
  vector<vector<int>> dp(n, vector<int>(SQRT, INF));
  vector<vector<bool>> inQ(n, vector<bool>(SQRT));
  dp[s][0] = 0;
  q.emplace(s, 0);
  inQ[s][0] = true;
  while (!q.empty()) {
    int u, p;
    tie(u, p) = q.front();
    q.pop();
    inQ[u][p] = false;
    if (p == 0) {
      for (int pp : g[u]) {
        if (pp < SQRT) {
          if (dp[u][pp] > dp[u][0]) {
            dp[u][pp] = dp[u][0];
            if (!inQ[u][pp]) {
              q.emplace(u, pp);
            }
          }
        } else {
          int cost = 0;
          for (int v = u - pp; v >= 0; v -= pp) {
            cost += 1;
            if (dp[v][0] > dp[u][0] + cost) {
              dp[v][0] = dp[u][0] + cost;
              if (!inQ[v][0]) {
                q.emplace(v, 0);
              }
            }
          }
          cost = 0;
          for (int v = u + pp; v < n; v += pp) {
            cost += 1;
            if (dp[v][0] > dp[u][0] + cost) {
              dp[v][0] = dp[u][0] + cost;
              if (!inQ[v][0]) {
                q.emplace(v, 0);
              }
            }
          }
        }
      }
    } else {
      if (dp[u][0] > dp[u][p]) {
        dp[u][0] = dp[u][p];
        if (!inQ[u][0]) {
          q.emplace(u, 0);
        }
      }
      for (int sgn : {-1, 1}) {
        int v = u + sgn * p;
        if (0 <= v && v < n && dp[v][p] > dp[u][p] + 1) {
          dp[v][p] = dp[u][p] + 1;
          if (!inQ[v][p]) {
            q.emplace(v, p);
          }
        }
      }
    }
  }
  if (dp[t][0] == INF) {
    cout << "-1\n";
  } else {
    cout << dp[t][0] << '\n';
  }
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int tests = 1;
  for (int tc = 0; tc < tests; ++tc) {
    testCase();
  }
  return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 43 / 43