경인지역 6개대학 연합 프로그래밍 경시대회 shake! 2017 본선 문제 풀이 슬라이드입니다.

1. 2017

2. A.
: ac: 36 / try: 45 / submission: 137
: ( )

3. A.
•
•
=> 1 == M ?
•
=> == 0 ?

4. A.
•
•
=> ???

5. A.
•
A B C D E
user1
user2
user3
user4
user5

6. A.
•
A B C D E
user1
user2
user3
user4
user5

7. A.
• .
A B C D E
user1
user2
user3
user4
user5

8. A.
•
A B C D E
user1
user2
user3
user4
user5

9. A.
•
A B C D E
user1
user2
user3
user4
user5

10. A.
• , .
• ( ), bit (DP) .

11. A.
• , .
=> O(N * M)
• ( ), bit (DP) .

12. B.
: ac: 0 / try: 7 / submission: 17
: ( )

13. B.
•
• (1, 1) (N, M) ,
• ?

14. B.
• ,
.
• -1 INFINITY .
• .

15. B. (1. flow)
• (1, 1) (N, M)
mincut .
• .
-1 5
7 10 3 4
12 3 8
1 7 -1

16. B. (1. flow)
• (1, 1) (N, M)
mincut .
• .
-1 5
7 10 3 4
12 3 8
1 7 -1

17. B. (1. flow)
• (1, 1) (N, M)
mincut .
• .
-1 5
7 10 3 4
12 3 8
1 7 -1

18. B. (1. flow)
(2,2)
in
(2,2)
out
Capacity : 1010

19. B. (1. flow)
(2,2)
in
(2,2)
out
10
-1
7 10
(2,1)
in
(2,1)
out
7
(1,1)
in
(1,1)
out
(1,2)
in
(1,2)
out
INF
INF
INF

20. B. (1. flow)
• Mincut = MaxFlow
•
.
• O((NM)^3)
• -> TLE
• .
-1 5
7 10 3 4
12 3 8
1 7 -1

21. B. (2. Dijkstra)
• S E !
• S E
.
S
E

22. B. (2. Dijkstra)
• S E !
• S E
.
•
.
S
E

23. B. (2. Dijkstra)
• S E !
• S E
.
•
.
S
E

24. B. (2. Dijkstra)
• S E !
• S E
.
•
.
S
E

25. B. (2. Dijkstra)
• S E !
• S E
.
•
.
S
E

26. B. (2. Dijkstra)
• S E !
• S E
.
•
.
-1
-1

27. B. (2. Dijkstra)
• S E !
• S E
.
•
.
-1
-1

28. B. (2. Dijkstra)
• S E !
• S E
.
•
.
-1
-1

29. C.
: ac: 4 / try: 16 / submission: 46
: ( )

30. C.
•
•
• X
•

31. C.
• K ,
• K
• K .
• X
K

32. C.
• K ,
• K .
• ,
• K .

33. C.
• K
• K .
• K .

34. C.
• K
• K .
• K .
• => Parametric Search

35. C.
• K
• K
• O(M * logK)

36. D.
: ac: 6 / try: 23 / submission: 63
: ( )

37. D.
•

38. D.
• 𝑏" .
• 𝑏" = ∑ (−1))
× 𝑘 + 1 ×𝑎)
./0
)1"
• 𝑏" 𝑏0
• 𝑏0 + 𝑏" = ∑ −1 )
×𝑎)
./0
)10 + 𝑎" + −1 ./0
×𝑛×𝑎"
• 𝑏3 + 𝑏0 = ∑ −1 )
×𝑎 )40 %.
./0
)10 + 𝑎0 + −1 ./0
×𝑛×𝑎0
• …

39. D.
• 𝑏0 + 𝑏" = ∑ −1 )
×𝑎)
./0
)10 + 𝑎" + −1 ./0
×𝑛×𝑎"
• 𝑏3 + 𝑏0 = ∑ −1 )
×𝑎 )40 %.
./0
)10 + 𝑎0 + −1 ./0
×𝑛×𝑎0
• …
• 𝑏" + 𝑏./0 = ∑ −1 )
×𝑎 )4./0 %.
./0
)10 + 𝑎./0 + −1 ./0
×𝑛×𝑎./0
• Dy[i] = ∑ −1 )
×𝑎)46
./0
)10 .
• Dy[i] (Dy[i] + Dy[i+1])
.

40. E.
: ac: 19 / try: 27 / submission: 64
: ( )

41. E.
,
K .

42. E.
𝑥 ,
𝑥 .
𝑥"
, 𝑥0
, 𝑥"
+𝑥0
, 𝑥3
, 𝑥3
+𝑥"
, 𝑥3
+𝑥0
, 𝑥3
+𝑥0
+ 𝑥"
, 𝑥;
, …
x .
1, 10, 11, 100, 101, 110, 111, 1000, ...

43. E.
1, 10, 11, 100, 101, 110, 111, 1000, ...
x K
K x .

44. E.
5 10 ,
10 1010(2)
1010(5) = 130 .

45. E.
K
x O(logK) ,
N
O(NlogK) .

46. F.
: ac: 0 / try: 1 / submission: 4
: ( )

47. F.
• N
•
• K X .
•

48. F.
• D[subroot][kcnt][xcnt]:
subroot kcnt K
xcnt

49. F.
• D[subroot][kcnt][xcnt]:
• subroot ,
• subroot
•
• .

50. F.
• D[subroot][kcnt][xcnt]:
• subroot
• K * X ,
• K * X
• N * K2 * X2

51. F.
• D[subroot][kcnt][xcnt]:
• subroot subtree M
•
• for(int k = 1; k <= K; k++)
for(int x = 0; x <= (M – k) / K; x++)

52. F.
• D[subroot][kcnt][xcnt]:
• D[subroot][1 ~ K][0 ~ (M – k) / K)]
• M .

53. F.
• D[subroot][kcnt][xcnt]:
• subtree M1,
• subtree M2
•
•

54. G.
: ac: 25 / try: 44 / submission: 110
: ( )

55. G.
•
.
, .
, .
,
.

56. G.
•
: Dynamic Programing
maxtable[i][j] : (i<=j) i j
i=j : i
i<j : max(i , maxtable[i+1][j])
table[i][j] :
(i<=j) i j ,
i=j : 0
i<j : i<=k<j k
min(table[i][k]+table[k+1][j]+abs(maxtable[i][k]- maxtable[k+1][j]))
• O(N^2)+O(N^3) = O(N^3)