結果

問題 No.2543 Many Meetings
ユーザー tnakao0123
提出日時 2024-06-19 13:21:08
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 103 ms / 2,000 ms
コード長 1,434 bytes
コンパイル時間 659 ms
コンパイル使用メモリ 46,972 KB
最終ジャッジ日時 2025-02-21 23:18:13
ジャッジサーバーID
(参考情報)
judge1 / judge3
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ファイルパターン 結果
sample AC * 3
other AC * 40
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp: In function ‘int main()’:
main.cpp:33:8: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   33 |   scanf("%d%d", &n, &k);
      |   ~~~~~^~~~~~~~~~~~~~~~
main.cpp:34:36: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   34 |   for (int i = 0; i < n; i++) scanf("%d%d", ls + i, rs + i);
      |                               ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

ソースコード

diff #
プレゼンテーションモードにする

/* -*- coding: utf-8 -*-
*
* 2543.cc: No.2543 Many Meetings - yukicoder
*/
#include<cstdio>
#include<algorithm>
#include<utility>
using namespace std;
/* constant */
const int MAX_N = 200000;
const int BN = 18;
const int INF = 1 << 30;
/* typedef */
using pii = pair<int,int>;
/* global variables */
int ls[MAX_N], rs[MAX_N], ps[MAX_N][BN];
pii rls[MAX_N], lis[MAX_N];
/* subroutines */
/* main */
int main() {
int n, k;
scanf("%d%d", &n, &k);
for (int i = 0; i < n; i++) scanf("%d%d", ls + i, rs + i);
for (int i = 0; i < n; i++) rls[i] = {rs[i], ls[i]};
sort(rls, rls + n);
int c = 0, m = 0;
for (int i = 0, pr = 0; i < n; i++) {
auto [ri, li] = rls[i];
if (pr <= li) c++, pr = ri;
if (m == 0 || lis[m - 1].first < li) lis[m++] = {li, i};
}
if (c < k) { puts("-1"); return 0; }
for (int i = 0; i < n; i++) {
auto [ri, li] = rls[i];
int j = lower_bound(lis, lis + m, pii(ri, -1)) - lis;
ps[i][0] = (j < m) ? lis[j].second : -1;
}
for (int i = 0; i < BN - 1; i++)
for (int u = 0; u < n; u++)
ps[u][i + 1] = (ps[u][i] >= 0) ? ps[ps[u][i]][i] : -1;
int minl = INF;
k--;
for (int u = 0; u < n; u++) {
int v = u;
for (int i = 0, bi = 1; v >= 0 && i < BN; i++, bi <<= 1)
if (k & bi) v = ps[v][i];
if (v < 0) break;
minl = min(minl, rls[v].first - rls[u].second);
}
printf("%d\n", (minl < INF) ? minl : -1);
return 0;
}
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