Submission #3711591

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Source Code Expand

#include <bits/stdc++.h>
#define FOR(v, a, b) for(int v = (a); v < (b); ++v)
#define FORE(v, a, b) for(int v = (a); v <= (b); ++v)
#define REP(v, n) FOR(v, 0, n)
#define REPE(v, n) FORE(v, 0, n)
#define REV(v, a, b) for(int v = (a); v >= (b); --v)
#define ALL(x) (x).begin(), (x).end()
#define LLI long long int
using namespace std;
template <typename T> using V = vector<T>;
template <typename T, typename U> using P = pair<T,U>;
template <typename I> void join(ostream &ost, I s, I t, string d=" "){for(auto i=s; i!=t; ++i){if(i!=s)ost<<d; ost<<*i;}ost<<endl;}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  LLI n,l; cin >> n >> l;

  vector<LLI> x(n);
  vector<char> d(n);
  REP(i,n) cin >> x[i] >> d[i];

  int cur = 0;
  LLI ans = 0;

  vector<LLI> L,R;
  while(cur < n && d[cur] == 'L'){
    L.push_back(x[cur]);
    ++cur;
  }

  REP(i,L.size()){
    ans += L[i]-(i+1);
  }

  while(cur < n){
    L.clear();
    R.clear();

    while(cur < n && d[cur] == 'R'){
      R.push_back(x[cur]);
      ++cur;
    }

    while(cur < n && d[cur] == 'L'){
      L.push_back(x[cur]);
      ++cur;
    }
    reverse(ALL(R));
    
    if(L.empty()){
      REP(i,R.size()){
	ans += l-i-R[i];
      }
    }else{
      LLI t = 0;

      LLI x = L.size() >= R.size() ? R[0] : L[0]-1;

      REP(i,R.size()) t += x-R[i]-i;
      REP(i,L.size()) t += L[i]-(x+1)-i;
      
      ans += t;
    }
  }

  cout << ans << endl;
  
  return 0;
}

Submission Info

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