Submission #101842

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Source Code Expand

#include <iostream>
#include <iomanip>
#include <sstream>
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <cassert>
#include <climits>
#include <queue>
#include <set>
#include <map>
#include <valarray>
#include <bitset>
#include <stack>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define chmax(a,b) (a<(b)?(a=b,1):0)
#define chmin(a,b) (a>(b)?(a=b,1):0)
#define valid(y,x,h,w) (0<=y&&y<h&&0<=x&&x<w)
typedef long long ll;
typedef pair<int,int> pii;
const int INF = 1<<29;
const double PI = acos(-1);
const double EPS = 1e-8;

const int MAX_N = 100000 * 2 + 10;
const int MAX_LOG_N = 20;
int N, M;
int s[MAX_N * 2], t[MAX_N * 2];

pii ps[MAX_N * 4];
int next[MAX_LOG_N][MAX_N * 2];

int solve() {
  int res = 0;

  for (int i = 0; i < N; ++i) {
    if (t[i] < s[i]) t[i] += M;
    s[N+i] = s[i] + M;
    t[N+i] = t[i] + M;
  }

  for (int i = 0; i < N * 2; ++i) {
    ps[i] = make_pair(t[i], i);
    ps[N*2 + i] = make_pair(s[i], N*2 + i);
  }
  sort(ps, ps + N*4);

  int last = -1;
  for(int i = N*4-1; i >= 0; --i) {
    int id = ps[i].second;
    if (id < N*2) {
      next[0][id] = last;
    } else {
      id -= N*2;
      if (last < 0 || t[last] > t[id]) {
        last = id;
      }
    }
  }

  for (int k = 0; k + 1 < MAX_LOG_N; ++k) {
    for (int i = 0; i < N * 2; ++i) {
      if (next[k][i] < 0) next[k+1][i] = -1;
      else next[k+1][i] = next[k][next[k][i]];
    }
  }

  for (int i = 0; i < N; ++i) {
    int tmp = 0, j = i;
    for (int k = MAX_LOG_N - 1; k >= 0; --k) {
      int j2 = next[k][j];
      if (j2 >= 0 && t[j2] <= s[i] + M) {
        j = j2;
        tmp |= 1<<k;
      }
    }
    res = max(res, tmp + 1);
  }
  return res;
}

int main() {
  cin>>N>>M;
  for (int i = 0; i < N; ++i) cin>>s[i]>>t[i];
  cout<<solve()<<endl;
}

Submission Info

Judge Result