Codeforces Round #322 (Div.2) Editorial

Revision en7, by fcspartakm, 2015-09-25 14:08:26

581A — ???

The first number in answer (number of days which Vasya can dress fashionably) is min(a, b) because every from this day he will dress one red sock and one blue sock.

After this Vasya will have either only red socks or only blue socks or socks do not remain at all. Because of that the second number in answer is max((a - min(a, b)) / 2, (b - min(a, b)) / 2).

Asymptotic behavior of this solution — O(1).

581B — ???

This problem can be solved in the following way. Let's iterate on given array from the right to the left and will store in variable maxH the maximal height if house which we have already considered.Then the answer to house number i is number max(0, maxH + 1 - hi), where hi number of floors in house number i.

Asymptotic behavior of this solution — O(n), where n — number of houses.

581C — ???

This problem can be solved in many ways, let's consider one of them.

The first step is to calculate sum of squares s of given rectangles. Then the side of a answer square is sqrt(s). If sqrt(s) is not integer print -1. Else we need to make the following.

We brute the order in which we will add given rectangles in the answer square (we can do it with help of next_permutation()) and for every order we brute will we rotate current rectangle on 90 degrees or not (we can do it with help of bit masks). In the beginning on every iteration the answer square c in which we add the rectangles is empty.

For every rectangle, which we add to the answer square we make the followin — we need to find the uppermost and leftmost empty cell free in answer square c (recall that we also brute will we rotate the current rectangle on 90 degrees or not). Now we try to impose current rectangle in the answer square c and the top left corner must coinside with the cell free. If current rectangle fully placed in the answer square c and does not intersect with the some rectangle which has already been added, we need to fill by the required letter appropriate cells in the answer square c.

If no one of the conditions did not disrupted after we added all three rectangles and all answer square c is fully filled by letters we found answer and we neeed only to print the answer square c.

Else if we did not find answer after all iterations on the rectangles — print -1.

For random number of the rectangles k asymptotic behavior — O(k! * 2k * s) where s — the sum of squares of the given rectangles.

Also this problem with 3 rectangles can be solved with the analysis of the cases with asymptotic O(s) where s — the sum of squares of given rectangles.

581D — ???

This problem can be solved in many ways. Let's consider the most intuitive way that fits in the given time.

In the beginning we need to sort given array in the following way — from two numbers to the left should be the number to which must be added fewer units of improvements to make it a multiple of 10. For example, if given array is {45, 30, 87, 26} after the sort the array must be equal to {87, 26, 45, 30}.

Now we iterate on the sorted array for i from 1 to n. Let's cur = 10 - (aimod10). If cur ≤ k assign ai = ai + cur and from k subtract cur else if cur > k break from cycle.

The next step is to iterate on array in the same way.

Now we need only to calculate answer ans — we iterate on array for i from 1 to n and assign ans = ans + (ai / 10).

Asymptotic behavior of this solution — O(n * log(n)) where n is the number of hero skills.

581E — ???

581F — ???

Tags editorial, round, 322, div2

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ru20 Russian fcspartakm 2015-09-28 14:02:11 0 (опубликовано)
en24 English fcspartakm 2015-09-28 12:09:42 67
ru19 Russian fcspartakm 2015-09-28 12:09:09 52
en23 English fcspartakm 2015-09-28 11:44:25 1251
en22 English fcspartakm 2015-09-28 11:26:03 19 Tiny change: ' $nv$.\n\nВторой с' -> ' $nv$.\n\nThe second case: \nВторой с'
en21 English fcspartakm 2015-09-28 11:24:50 1646
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en11 English fcspartakm 2015-09-28 09:50:45 2047
ru18 Russian fcspartakm 2015-09-28 09:44:09 5082
ru17 Russian fcspartakm 2015-09-28 09:28:09 53
en10 English fcspartakm 2015-09-28 09:26:00 2114
ru16 Russian fcspartakm 2015-09-28 09:24:06 2118
ru15 Russian fcspartakm 2015-09-25 16:10:45 56
en9 English fcspartakm 2015-09-25 14:10:24 1 Tiny change: 'e followin — w' -> 'e following — w'
en8 English fcspartakm 2015-09-25 14:08:26 0 Tiny change: ' degrees ot not (we c' -> ' degrees or not (we c'
en7 English fcspartakm 2015-09-25 14:08:26 2 Tiny change: ' degrees ot not (we c' -> ' degrees or not (we c'
en6 English fcspartakm 2015-09-25 14:07:35 2756
en5 English fcspartakm 2015-09-25 13:51:07 2 Tiny change: ' to iterato on array ' -> ' to iterate on array '
en4 English fcspartakm 2015-09-25 13:50:34 532
en3 English fcspartakm 2015-09-25 13:17:49 703
en2 English fcspartakm 2015-09-25 13:08:32 530
en1 English fcspartakm 2015-09-25 13:04:29 4088 Initial revision for English translation
ru14 Russian fcspartakm 2015-09-25 12:36:42 8
ru13 Russian fcspartakm 2015-09-25 12:36:00 941
ru12 Russian fcspartakm 2015-09-25 11:51:25 4
ru11 Russian fcspartakm 2015-09-25 11:51:12 1 Мелкая правка: 'вадрате $c (напомним' -> 'вадрате $c$ (напомним'
ru10 Russian fcspartakm 2015-09-25 11:50:57 47
ru9 Russian fcspartakm 2015-09-25 11:49:20 1 Мелкая правка: 'mutation()$, а такж' -> 'mutation())$, а такж'
ru8 Russian fcspartakm 2015-09-25 11:48:50 2 Мелкая правка: 'ощью $next/_permutati' -> 'ощью $next\_permutati'
ru7 Russian fcspartakm 2015-09-25 11:48:37 1
ru6 Russian fcspartakm 2015-09-25 11:48:16 1510
ru5 Russian fcspartakm 2015-09-24 17:35:56 319
ru4 Russian fcspartakm 2015-09-24 17:26:14 2 Мелкая правка: '------\n\n[581D ' -> '------\n\n\n[581D '
ru3 Russian fcspartakm 2015-09-24 17:25:35 337
ru2 Russian fcspartakm 2015-09-24 17:23:17 53
ru1 Russian fcspartakm 2015-09-24 17:22:02 996 Первая редакция (сохранено в черновиках)