Submission #224516

#	Time	Username	Problem	Language	Result	Execution time	Memory
224516		Nightlight	Solar Storm (NOI20_solarstorm)	C++14	100 / 100	984 ms	243836 KiB

SolarStorm

#include <bits/stdc++.h>
#define dist(a, b) (pos[a] - pos[b])
using namespace std;

long long N, K, S;
long long pos[1000005];
long long pre[1000005];
long long sh[1000005];
long long T[1000005][25];
vector<int> loc;

int lift(int u, int f) {
  for(int i = 20; i >= 0; i--) {
    if(f >= (1 << i)) {
      f -= (1 << i);
      u = T[u][i];
    }
  }
  return u;
}

int main() {
//  freopen("inp", "r", stdin);
  scanf("%lld %lld %lld", &N, &S, &K);
  for(int i = 2; i <= N; i++) {
    scanf("%lld", &pos[i]);
    pos[i] += pos[i - 1];
  }
  for(int i = 1; i <= N; i++) {
    scanf("%lld", &pre[i]);
    pre[i] += pre[i - 1];
  }
  //precompute reach dalam O(N)
  deque<long long> L, mid;
  for(int R = 1; R <= N; R++) {
    while(!mid.empty() && dist(R, mid.front()) > K) mid.pop_front();
    if(mid.empty()) L.clear();
    else {
      while(!L.empty() && dist(mid.front(), L.front()) > K) L.pop_front();
    }
    if(mid.empty()) {
      sh[R] = R;
      T[R][0] = R - 1;
    }else if(L.empty()) {
      sh[R] = mid.front();
      T[R][0] = mid.front() - 1;
    }else {
      sh[R] = mid.front();
      T[R][0] = L.front() - 1;
    }
    mid.push_back(R);
    L.push_back(R);
  }
  //precomputebinary lift
  for(int j = 1; j <= 20; j++) {
    for(int i = 1; i <= N; i++) {
      T[i][j] = T[T[i][j - 1]][j - 1];
    }
  }
  //binary lift coba semua kemungkinan
  int opt;
  long long ans = 0, id, res;
  for(int i = S; i <= N; i++) {
    opt = lift(i, S);
    res = pre[i] - pre[opt];
    if(ans < res) {
      ans = res;
      id = i;
    } 
  }
  //bruteforce jawaban
  int krg = S, p = id;
  while(krg > 0 && p != 0) {
    loc.push_back(sh[p]);
    p = T[p][0];
    krg--;
  }
  printf("%lld\n", S - krg);
  for(int i : loc) {
    printf("%d ", i);
  }
}

Compilation message (stderr)

SolarStorm.cpp: In function 'int main()':
SolarStorm.cpp:24:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld %lld %lld", &N, &S, &K);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SolarStorm.cpp:26:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld", &pos[i]);
     ~~~~~^~~~~~~~~~~~~~~~~
SolarStorm.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld", &pre[i]);
     ~~~~~^~~~~~~~~~~~~~~~~
SolarStorm.cpp:72:16: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized]
   int krg = S, p = id;
                ^

• Subtask 1: 10 / 10
• Subtask 2: 7 / 7
• Subtask 3: 11 / 11
• Subtask 4: 8 / 8
• Subtask 5: 18 / 18
• Subtask 6: 16 / 16
• Subtask 7: 30 / 30