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  1. /* g++ -O2 -std=c++11 */
  2.  
  3. /* input/output streams and formatting */
  4. 	#include <iostream>
  5. 	#include <cstdio>
  6. 	#include <sstream>
  7. 	#include <iomanip>
  8.  
  9. /* data structures */
  10. 	#include <vector>
  11. 	#include <map>
  12. 	#include <stack>
  13. 	#include <queue>
  14. 	#include <deque>
  15. 	#include <set>
  16. 	#include <bitset>
  17. 	#include <unordered_map>	
  18.  
  19. /* useful libs */
  20. 	#include <cstring>
  21. 	#include <cstdlib>
  22. 	#include <algorithm>
  23. 	#include <cmath>
  24. #ifdef LOCAL_DEBUG
  25. 	#include <ctime>
  26. #endif
  27.  
  28. /* don't use this shit in your projects, 
  29.  * it's only useful in olympiads ! 
  30.  */
  31. 	using namespace std;
  32.  
  33. /* some useful defines */
  34. 	#define fi first
  35. 	#define se second
  36. 	#define pb(x) push_back(x)
  37. 	#define ppb(x) pop_back(x)
  38. 	#define mp(x, y) make_pair((x), (y))
  39. 	#define all(a) (a).begin(), (a).end()
  40. 	#define rall(a) (a).rbegin(), (a).rend()
  41. 	#define forn(i, n) for(int i=0; i<(n); i++)
  42. 	#define for1(i, n) for(int i=1; i<=(n); i++)
  43. 	#define forr(i, n) for(int i=(n); i-->0; )
  44. 	#define forab(i, a, b) for (int i=(int)(a); i<(int)(b); i++)
  45.  
  46. /* commonly used types */
  47. 	typedef pair<int, int> pii;
  48. 	typedef vector<int> vi;
  49. 	typedef vector<pii> vpi;
  50. 	typedef vector<vi> vvi;
  51. 	typedef long long i64;
  52. 	typedef vector<i64> vi64;
  53. 	typedef vector<vi64> vv64;
  54. 	typedef pair<i64, i64> pi64;
  55.  
  56. /* geometric types */
  57. 	template <typename T> struct point2d { T x; T y; };
  58. 	template <typename T> struct line2d { T a; T b; T c; };
  59. 	template <typename T> struct circle2d { point2d<T> c; T r; };
  60. 	typedef point2d<int> p2i;
  61. 	typedef point2d<double> p2f;
  62. 	typedef line2d<int> l2i;
  63. 	typedef line2d<double> l2f;
  64. 	typedef circle2d<int> c2i;
  65. 	typedef circle2d<double> c2f;
  66.  
  67.  
  68. #define su(m) ((m)*((m)+1))/2
  69. i64 find(i64 a, i64 b, i64 k){
  70. 	i64 m = (a + b)/(i64)2;
  71. 	if (su(m) < k && su(m+1) >= k)
  72. 		return m;
  73. 	if (su(m) > k)
  74. 		return find(a, m, k);
  75. 	else
  76. 		return find(m+1, b, k);
  77. }
  78.  
  79.  
  80. int a;
  81. int main()
  82. {
  83. 	// input/output manipulation
  84. 	ios::sync_with_stdio(false);
  85. 	cout.precision(10);
  86. 	cout << fixed;
  87.  
  88. 	// write the solution here
  89.  
  90. 	i64 n, k;
  91. 	scanf("%ld%ld", &n, &k);
  92.  
  93.     cout << n << " " << k << endl;
  94.     exit(0);
  95.  
  96. 	i64 m = std::sqrt(k);
  97. 	if (su(m-1) < k && su(m) >= k)
  98. 		m = m-1;
  99. 	if (su(m) < k && su(m+1) >= k)
  100. 		m = m;
  101. 	if (su(m+1) < k && su(m+2) >= k)
  102. 		m = m+1;
  103. 	// n*(n+1)/2 <= k;
  104. 	// n(n+1) <= 2k
  105. 	//i64 m = find(0, k, k);
  106. 	int l = k - su(m) - 1;
  107. 	forn(i, n){
  108. 		scanf("%d", &a);
  109. 		if (i == l){
  110. 			printf("%d\n", a);
  111. 			break;;
  112. 		}
  113. 	}
  114.  
  115.  
  116. #ifdef LOCAL_DEBUG
  117. 	cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s." << endl;
  118. #endif
  119. 	return 0;
  120. }
Success #stdin #stdout 0s 3460KB
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-5225681348924014590 577738187246403586
https://ideone.com/NDPC4R
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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