Submission #986791

#	Time	Username	Problem	Language	Result	Execution time	Memory
986791		cig32	Lamps (JOI19_lamps)	C++17	4 / 100	26 ms	27720 KiB

lamp

#include "bits/stdc++.h"
#define int long long
using namespace std;
mt19937_64 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  return uniform_int_distribution<int>(x, y)(rng);
}
const int MAXN = 1e6 + 10;
string a, b;
int n;
int ps[MAXN];
int dpf(int l, int r, int tog) {
  while(l <= r && (a[l] ^ tog) == b[l]) l++;
  while(l <= r && (a[r] ^ tog) == b[r]) r--;
  if(l > r) return 0;
  int nums = ps[r] - ps[l];
  int cnt0, cnt1;
  if(nums % 2 == 1) {
    cnt0 = cnt1 = (nums + 1) / 2;
  }
  else {
    cnt0 = nums / 2 + 1, cnt1 = nums / 2;
    if(b[l] == '1') swap(cnt0, cnt1);
  }
  //cout << l << " " << r << " " << cnt0 << " " << cnt1 << "\n";
  // set, then bruhopen
  int ans = 1 + min(cnt0, cnt1);
  ans = min(ans, 1 + dpf(l, r, tog ^ 1));
  return ans;
}
void solve(int tc) {
  cin >> n;
  cin >> a >> b;
  a = " " + a;
  b = " " + b;
  for(int i=2; i<=n; i++) ps[i] = ps[i-1] + (b[i] != b[i-1]);
  cout << dpf(1, n, 0) << '\n';
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int t = 1;
  // cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}
/*
g++ T2421.cpp -std=c++17 -O2 -o T2421
./T2421 < input.txt
*/

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 4 / 4
• Subtask 4: 0 / 49