选择客栈

题目地址：

https://ac.nowcoder.com/acm/problem/16594

基本思路：

参考代码：

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include <bits/stdc++.h>
using namespace std;
#define IO std::ios::sync_with_stdio(false); cin.tie(0)
#define int long long
#define SZ(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rep(i, l, r) for (int i = l; i <= r; i++)
#define per(i, l, r) for (int i = l; i >= r; i--)
#define mset(s, _) memset(s, _, sizeof(s))
#define pb push_back
#define pii pair <int, int>
#define mp(a, b) make_pair(a, b)
#define INF 0x3f3f3f3f

inline int read() {
  int x = 0, neg = 1; char op = getchar();
  while (!isdigit(op)) { if (op == '-') neg = -1; op = getchar(); }
  while (isdigit(op)) { x = 10 * x + op - '0'; op = getchar(); }
  return neg * x;
}
inline void print(int x) {
  if (x < 0) { putchar('-'); x = -x; }
  if (x >= 10) print(x / 10);
  putchar(x % 10 + '0');
}

const int maxn = 2e5 + 10;
int n,k,p,c[maxn],w[maxn],cnt[maxn][55];
signed main() {
  IO;
  cin >> n >> k >> p;
  rep(i, 1, n) cin >> c[i] >> w[i];
  mset(cnt,0);
  per(i,n,1){
    rep(j,0,k - 1) cnt[i][j] += cnt[i + 1][j];
    cnt[i][c[i]]++;
  }
  int lst = n + 1,ans = 0;
  per(i,n,1){
    if(w[i] <= p) lst = i;
    ans += cnt[lst][c[i]];
    if(w[i] <= p) ans--; // 不能选择同一个客栈;
  }
  cout << ans << '\n';
  return 0;
}