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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#611720#8939. PermutationUESTC_OldEastWestWA 75ms167336kbC++202.3kb2024-10-04 22:19:362024-10-04 22:19:36

Judging History

This is the latest submission verdict.

  • [2024-10-04 22:19:36]
  • Judged
  • Verdict: WA
  • Time: 75ms
  • Memory: 167336kb
  • [2024-10-04 22:19:36]
  • Submitted

answer

#pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
const int N = 1e6 + 5;
const int M = 31;
const int INF = 1e9;
const double eps = 1e-8;
std::vector<std::vector<int> > dp, f;

void prep() {
  f = std::vector<std::vector<int> > (N, std::vector<int> (M));

//  std::function<int(int, int)> DFS = [&](int n, int m) {
//    if (n <= 1) return 0;
//    if (m <= -1) return INF;
//    if (dp[n][m]) return dp[n][m];
//
//    dp[n][m] = INF;
//    int mid = n - n / 3;
//    for (int i = std::max(1, mid - 500); i < std::min(n, mid + 500); i += 1) {
//      int new_val = std::max(DFS(i, m - 1), DFS(n - i, m - 2) + n - i) + i;
//      if (new_val < dp[n][m]) f[n][m] = i, dp[n][m] = new_val;
//    }
//
//    return dp[n][m];
//  };
//
//  for (int i = 2; i < N; ++i) {
//    int k = int(1.5 * log(i) / log(2) + 1.0);
//    for (int j = std::max(0, k - 3); j < k; ++j) DFS(i, j);
//    if (DFS(i, k - 1) > 2 * i || !f[i][k - 1]) std::cout << '!';
//  }
	for (int i = 0; i < N; ++i) {
		for (int j = 0; j < M; ++j) {
			f[i][j] = int(i * 0.618);
		}
	}
}

void charming() {
  int n; std::cin >> n;

  std::function<int(int, int)> Send = [&](int l, int r) {
    if (l == r) return -1;
    std::cout << "? " << l << ' ' << r << '\n';
    std::cout.flush();
    int rcv; std::cin >> rcv;
    return rcv;
  };
  
  std::function<void(int)> Answer = [&](int x) {
    std::cout << "! " << x << '\n';
    std::cout.flush();
  };

  int remain = int(1.5 * (log(n) / log(2)) + 1.0 + eps);
//  std::cout << remain << '\n';
  int l = 1, r = n, p = -1;
  while (l < r) {
    if (p == -1) p = Send(l, r), --remain;

    if (l + 1 == r) {
      if (p == l) ++l;
      break;
    }
    int ask_len = f[r - l + 1][remain];
    if (l + ask_len - 1 >= p) {
      int q = Send(l, l + ask_len - 1); --remain;
      if (q == p) r = l + ask_len - 1;
      else l = l + ask_len, p = -1;
    }
    else {
      int q = Send(r - ask_len + 1, r); --remain;
      if (q == p) l = r - ask_len + 1;
      else r = r - ask_len, p = -1;
    }
  }
  Answer(l);
}

signed main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(NULL);
  std::cout.tie(NULL);
  prep();
  int t; std::cin >> t;
  while (t--) charming();
  return 0;
}

详细

Test #1:

score: 100
Accepted
time: 75ms
memory: 167336kb

input:

3
5
3
2
5
6
6
5
3
1
4
3
3

output:

? 1 5
? 1 3
? 4 5
! 4
? 1 6
? 4 6
? 1 3
? 1 2
! 2
? 1 4
? 3 4
! 4

result:

ok Correct (3 test cases)

Test #2:

score: -100
Wrong Answer
time: 66ms
memory: 167012kb

input:

10000
10
2
2
3
5
5
10
10
10
8
5
7
10
5
1
10
9
8
10
4
4
6
2
1

output:

? 1 10
? 1 6
? 1 3
? 4 6
? 4 5
! 4
? 1 10
? 5 10
? 8 10
? 5 7
? 6 7
! 6
? 1 10
? 1 6
? 7 10
? 9 10
? 7 8
! 7
? 1 10
? 1 6
? 4 6
? 1 3
? 1 2
! 2

result:

wrong answer Wrong prediction (test case 4)