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ASSIGN - Assignments |
Problem
Your task will be to calculate number of different assignments of n different topics to n students such that everybody gets exactly one topic he likes.
Input
First line of input contains number of test cases c (1 ≤ c ≤ 80). Each test case begins with number of students n (1 ≤ n ≤ 20). Each of the next n lines contains n integers describing preferences of one student. 1 at the ith position means that this student likes ith topic, 0 means that he definitely doesn't want to take it.
Output
For each test case output number of different assignments (it will fit in a signed 64-bit integer).
Example
Input: 3 3 1 1 1 1 1 1 1 1 1 11 1 0 0 1 0 0 0 0 0 1 1 1 1 1 1 1 0 1 0 1 0 0 1 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 0 1 1 0 1 1 0 1 1 1 0 1 0 0 1 1 1 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 1 0 1 1 0 0 0 0 0 0 1 0 0 1 0 1 1 0 0 0 1 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 0 1 1 1 1 0 0 0 11 0 1 1 1 0 1 0 0 0 1 0 0 0 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 0 0 0 1 0 0 1 0 1 0 1 0 1 0 1 1 1 0 0 1 0 0 0 0 1 0 1 0 0 1 0 1 1 0 0 0 0 1 1 0 1 0 1 1 1 0 1 1 0 1 0 1 1 0 1 1 0 0 1 0 0 0 1 1 0 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 1 0 1 Output: 6 7588 7426
Added by: | gawry |
Date: | 2005-10-08 |
Time limit: | 2.997s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: NODEJS PERL6 VB.NET |
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2025-08-23 00:09:29
Adivce to get the most out of the problem. fisrt solve it rec in O(n*n*2^) , optim1 the the loop inside the resuive function u can iterate only on the set bits no only the n every loop using popcount or__lg, optim2 the first state is always know the person u assign to the job is always equal the num of set bits in the mask so u can git red of thi state by using popcount comp(n * 2^n). optim3 since u will only traverse in the matrix the set bits ones just store only the only in vector<int> arr[20] it geta big boost boost in the compexity. optim4 solve it using bottom up and get rif of the stack use push dp, pull dp |
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2022-11-28 05:02:24
Iterate through the bits like we do in fenwick tree with dp it works:) |
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2022-10-04 04:10:13
dp[20][(1<<20)-1] works Last edit: 2022-10-04 04:10:36 |
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2022-06-05 02:13:37
Cool problem! |
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2022-01-18 15:58:58
Nice problem. Dp with bitmasks should do it |
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2021-12-15 13:39:45
how (2^n * n) complexity is accepted, time complexity according to this coming in range 10^9? |
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2021-06-26 16:53:19
Can explain O(2^n*n) complexity approach plz! Mine was O(n*n*2^n) with optimization. |
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2021-06-08 08:11:50
use row...keep a mask to check which index you have been taken i mean which assignment...mask can use with bit operation. use a for loop between the recursive solution. if you on a position on mask dont forget to off it after the iteration |
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2021-02-18 10:20:22
use-> unsigned long long Good problem |
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2021-01-30 12:48:33
@brokeboy, my code having similar complexities, but I am getting TLE. Do you have any clue, I am using a 2-d vector and adjacency matrix to store preferences. Edit: how you got AC with that complexity( Time: O( 2 ^ 20 * n * n * c), 2 ^ 20 * n * n * c = 1M * 20 * 20 * 80 = 1M * 32 * 1000 = 32 * 10 ^ 9) Last edit: 2021-01-30 12:53:27 |