oj.uz

Submission #251605

# Submission time Handle Problem Language Result Execution time Memory
251605 2020-07-22T03:13:03 Z cjoa Data Transfer (IOI19_transfer) C++14
100 / 100
 115 ms 2680 KB 
#include "transfer.h"

using namespace std;

#include <cstdio>
#include <cassert>

std::vector<int> get_attachment(std::vector<int> source) {
   int N = source.size();
   assert(N == 63 || N == 255);
   source.push_back(0);
   ++N;
   vector<int> res;
   for (int len = N/2; len > 0; len /= 2) {
      int bit = 0;
      for (int start = 0; start < N; start += len*2) {
         for (int i = 0; i < len; ++i)
            bit ^= source[start + i];
      }
      res.push_back(bit);
   }
   int tbit = 0;
   for (int x : res)
      tbit ^= x;
   res.push_back(tbit);
   /*
   for (int x : res)
      fprintf(stderr, "%d", x);
   fprintf(stderr, "\n");
   */
   return res;
}

std::vector<int> retrieve(std::vector<int> data) {
   assert(data.size() == 63 + 7 || data.size() == 255 + 9);

   int N, K;
   if (data.size() == 63+7)
      N = 63, K = 7;
   else
      N = 255, K = 9;

   vector<int> checkbits(data.begin()+N, data.end());
   data.erase(data.begin()+N, data.end());

   /*
   fprintf(stderr, "data:");
   for (int x : data)
      fprintf(stderr, "%d", x);
   fprintf(stderr, "\n");

   fprintf(stderr, "checkbits:");
   for (int x : checkbits)
      fprintf(stderr, "%d", x);
   fprintf(stderr, "\n");
   */

   assert((int) data.size() == N);
   assert((int) checkbits.size() == K);

   int last_bit = checkbits.back();
   checkbits.pop_back();
   --K;

   // check bit on trailer info:
   int tbit = 0;
   for (int k = 0; k < K; ++k)
      tbit ^= checkbits[k];

   if (tbit != last_bit)
      return data;

   int L = 0, R = N;
   ++N;
   for (int k = 0, len = N/2; len > 0; ++k, len /= 2) {
      assert(k < K);
      int bit = 0;
      for (int start = 0; start < N; start += len*2) {
         for (int i = 0; i < len; ++i)
            bit ^= data[start + i];
      }
   // fprintf(stderr, "k:%d  len:%d   L:%d  R:%d  bit:%d  checkbit:%d\n",
   //         k, len, L, R, bit, checkbits[k]);
      int mid = (L + R) / 2;
      if (bit != checkbits[k]) {
         R = mid;
      }
      else {
         L = mid+1;
      }
   }
// fprintf(stderr, "L: %d  R: %d\n", L, R);
   assert(L == R);
   if (L < (int) data.size())
      data[L] ^= 1;

   return data;
}

Subtask #1
60.0 / 60.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1144 KB Output is correct
2 Correct 4 ms 912 KB Output is correct
3 Correct 3 ms 1040 KB Output is correct
4 Correct 4 ms 1152 KB Output is correct
5 Correct 3 ms 1152 KB Output is correct
6 Correct 4 ms 1148 KB Output is correct
7 Correct 3 ms 912 KB Output is correct
8 Correct 4 ms 1144 KB Output is correct
9 Correct 4 ms 1040 KB Output is correct
10 Correct 3 ms 912 KB Output is correct
11 Correct 4 ms 1040 KB Output is correct
12 Correct 4 ms 1152 KB Output is correct
13 Correct 4 ms 912 KB Output is correct
14 Correct 4 ms 1144 KB Output is correct
15 Correct 3 ms 912 KB Output is correct
16 Correct 4 ms 1144 KB Output is correct
17 Correct 3 ms 912 KB Output is correct

Subtask #2
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 97 ms 2668 KB Output is correct
2 Correct 99 ms 2668 KB Output is correct
3 Correct 101 ms 2676 KB Output is correct
4 Correct 101 ms 2500 KB Output is correct
5 Correct 98 ms 2672 KB Output is correct
6 Correct 99 ms 2680 KB Output is correct
7 Correct 98 ms 2676 KB Output is correct
8 Correct 114 ms 2668 KB Output is correct
9 Correct 99 ms 2672 KB Output is correct
10 Correct 99 ms 2672 KB Output is correct
11 Correct 99 ms 2672 KB Output is correct
12 Correct 115 ms 2664 KB Output is correct
13 Correct 102 ms 2588 KB Output is correct
14 Correct 100 ms 2668 KB Output is correct
15 Correct 114 ms 2668 KB Output is correct
16 Correct 99 ms 2672 KB Output is correct
17 Correct 110 ms 2672 KB Output is correct
18 Correct 98 ms 2668 KB Output is correct
19 Correct 101 ms 2628 KB Output is correct