Submission #416908

#	Time	Username	Problem	Language	Result	Execution time	Memory
416908		Mamnoon_Siam	Wild Boar (JOI18_wild_boar)	C++17	100 / 100	10593 ms	712724 KiB

wild_boar

#include <bits/stdc++.h>
using namespace std;

using ii = pair<int, int>;
using ll = long long;
using vi = vector<int>;
#define fi first
#define se second
#define all(v) begin(v), end(v)
#define sz(v) (int)(v.size())
using pli = pair<ll, int>;
template<typename T>
inline void chkmin(T& x, T y) {
  x = x < y ? x : y;
}

const ll inf = 1e18;

tuple<ll,int,int> shortest_path(vector<pair<ii,ll>>& ls, int anot, int bnot) {
  // best path *---a--->--...-->---b---* in ls s.t. a != anot, b != bnot
  tuple<ll,int,int> opt{inf, -1, -1};
  for(auto [pa, w] : ls) {
    auto [s, t] = pa;
    if(s != anot and t != bnot) {
      opt = min(opt, make_tuple(w, s, t));
    }
  }
  return opt;
}

struct path {
  int s, t;
  ll w;
};

vector<path> get_top5(vector<pair<ii,ll>>& ls) {
  vector<path> ret;
  auto [w1, a1, b1] = shortest_path(ls, -1, -1);
  auto [w2, a2, b2] = shortest_path(ls, a1, -1);
  auto [w3, a3, b3] = shortest_path(ls, a1, b2);
  auto [w4, a4, b4] = shortest_path(ls, -1, b1);
  auto [w5, a5, b5] = shortest_path(ls, a4, b1);
  if(~a1) ret.push_back({a1, b1, w1});
  if(~a2) ret.push_back({a2, b2, w2});
  if(~a3) ret.push_back({a3, b3, w3});
  if(~a4) ret.push_back({a4, b4, w4});
  if(~a5) ret.push_back({a5, b5, w5});
  return ret;
}

vector<path> merge(vector<path> L, vector<path> R) {
  map<ii, ll> opt;
  for(path& l : L) {
    for(path& r : R) {
      if(l.t != r.s) {
        if(!opt.count(ii(l.s, r.t))) {
          opt[ii(l.s, r.t)] = l.w + r.w;
        } else {
          chkmin(opt[ii(l.s, r.t)], l.w + r.w);
        }
      }
    }
  }
  std::vector<path> ret;
  vector<pair<ii,ll>> ls(all(opt));
  return get_top5(ls);
}

int n, m, T, L;
int A[4004], B[4004], C[4004];
vi ine[2002], oute[2002];
ll cost[4004][4004]; // cost[i][j] = shortest path from i-th directed edge to j-th directed edge
int X[100005];
vector<path> top5[2002][2002];
vector<path> tree[100005 << 2];

void build(int u = 1, int b = 1, int e = L-1) {
  if(b == e) {
    tree[u] = top5[X[b]][X[b+1]];
    return;
  }
  int mid = (b + e) >> 1;
  build(u << 1, b, mid);
  build(u << 1 | 1, mid+1, e);
  tree[u] = merge(tree[u << 1], tree[u << 1 | 1]);
}

void update(int pos, int u = 1, int b = 1, int e = L-1) {
  if(b == e) {
    tree[u] = top5[X[b]][X[b+1]];
    return;
  }
  int mid = (b + e) >> 1;
  if(pos <= mid)
    update(pos, u << 1, b, mid);
  else
    update(pos, u << 1 | 1, mid+1, e);
  tree[u] = merge(tree[u << 1], tree[u << 1 | 1]);
}

#ifdef LOCAL
#include "../debug.h"
#else
#define debug(...)
#endif
int main(int argc, char const *argv[])
{
#ifdef LOCAL
  freopen("in", "r", stdin);
#endif
  scanf("%d %d %d %d", &n, &m, &T, &L);
  for(int i = 1; i <= m; ++i) {
    scanf("%d %d %d", &A[2*i], &B[2*i], &C[2*i]);
    A[2*i+1] = B[2*i];
    B[2*i+1] = A[2*i];
    C[2*i+1] = C[2*i];
    ine[B[2*i]].emplace_back(2*i);
    oute[A[2*i]].emplace_back(2*i);
    ine[B[2*i+1]].emplace_back(2*i+1);
    oute[A[2*i+1]].emplace_back(2*i+1);
  }
  for(int i = 1; i <= n; ++i) {
    debug(ine[i], oute[i]);
  }
  for(int i = 1; i <= L; ++i) {
    scanf("%d", &X[i]);
  }
  for(int src = 2; src <= 2*m+1; ++src) {
  // for(int src : {4}) {
    vector<bool> done(2*m+2);
    ll *dis = cost[src];
    fill(dis+2, dis+2*m+2, inf);
    debug(vector<ll>(dis+2, dis+2*m+2));
    dis[src] = C[src];
    debug(dis[src]);
    priority_queue<pli, vector<pli>, greater<pli>> Q;
    Q.emplace(dis[src], src);
    while(sz(Q)) {
      int u = Q.top().se;
      debug(u);
      Q.pop();
      if(done[u]) continue;
      done[u] = 1;
      for(int v : oute[B[u]]) if((u^v)>>1) {
        debug(v);
        ll nw = dis[u] + C[v];
        debug(nw);
        debug(dis[7]);
        if(nw < dis[v]) {
          dis[v] = nw;
          Q.emplace(dis[v], v);
        }
      }
    }
    debug(dis[7]);
  }
  for(int a = 1; a <= n; ++a) {
    for(int b = 1; b <= n; ++b) if(a != b) {
      vector<pair<ii,ll>> ls;
      for(int s : oute[a])
        for(int t : ine[b])
          if(cost[s][t] < inf)
            ls.push_back({{s>>1, t>>1}, cost[s][t]});
      top5[a][b] = get_top5(ls);
    }
  }
  build();
  while(T--) {
    int p, q;
    scanf("%d %d", &p, &q);
    X[p] = q;

    update(p-1);
    update(p);

    ll ans = inf;
    for(path& pa : tree[1]) chkmin(ans, pa.w);
    printf("%lld\n", ans == inf ? -1 : ans);
  }
  return 0;
}

Compilation message (stderr)

wild_boar.cpp: In function 'int main(int, const char**)':
wild_boar.cpp:111:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |   scanf("%d %d %d %d", &n, &m, &T, &L);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
wild_boar.cpp:113:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |     scanf("%d %d %d", &A[2*i], &B[2*i], &C[2*i]);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
wild_boar.cpp:126:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |     scanf("%d", &X[i]);
      |     ~~~~~^~~~~~~~~~~~~
wild_boar.cpp:170:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  170 |     scanf("%d %d", &p, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 12 / 12
• Subtask 2: 35 / 35
• Subtask 3: 15 / 15
• Subtask 4: 38 / 38