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Educational Codeforces Round 165 (Rated for Div. 2)
21:09:04
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Difficulty:
—
hashing
combine-tags-by-or
*combine tags by OR
2-sat
binary search
bitmasks
brute force
chinese remainder theorem
combinatorics
constructive algorithms
data structures
dfs and similar
divide and conquer
dp
dsu
expression parsing
fft
flows
games
geometry
graph matchings
graphs
greedy
hashing
implementation
interactive
math
matrices
meet-in-the-middle
number theory
probabilities
schedules
shortest paths
sortings
string suffix structures
strings
ternary search
trees
two pointers
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Problems
#
Name
4C
Registration System
data structures
,
hashing
,
implementation
1300
x76805
1520D
Same Differences
data structures
,
hashing
,
math
1200
x42428
2A
Winner
hashing
,
implementation
1500
x24855
1800D
Remove Two Letters
data structures
,
greedy
,
hashing
,
strings
1200
x21612
126B
Password
binary search
,
dp
,
hashing
,
string suffix structures
,
strings
1700
x17690
486B
OR in Matrix
greedy
,
hashing
,
implementation
1300
x16910
1650C
Weight of the System of Nested Segments
greedy
,
hashing
,
implementation
,
sortings
1200
x16340
1451C
String Equality
dp
,
greedy
,
hashing
,
implementation
,
strings
1400
x15193
525A
Vitaliy and Pie
greedy
,
hashing
,
strings
1100
x13836
1553B
Reverse String
brute force
,
dp
,
hashing
,
implementation
,
strings
1300
x13795
1536C
Diluc and Kaeya
data structures
,
dp
,
hashing
,
number theory
1500
x13521
1527C
Sequence Pair Weight
hashing
,
implementation
,
math
1600
x13089
1537E1
Erase and Extend (Easy Version)
binary search
,
brute force
,
dp
,
greedy
,
hashing
,
implementation
,
string suffix structures
,
strings
,
two pointers
1600
x12223
1899D
Yarik and Musical Notes
hashing
,
math
,
number theory
1300
x12116
1360F
Spy-string
bitmasks
,
brute force
,
constructive algorithms
,
dp
,
hashing
,
strings
1700
x11828
1326D1
Prefix-Suffix Palindrome (Easy version)
hashing
,
string suffix structures
,
strings
1500
x11585
1133D
Zero Quantity Maximization
hashing
,
math
,
number theory
1500
x10907
559B
Equivalent Strings
divide and conquer
,
hashing
,
sortings
,
strings
1700
x10355
1895C
Torn Lucky Ticket
brute force
,
dp
,
hashing
,
implementation
,
math
1400
x10050
1849C
Binary String Copying
binary search
,
brute force
,
data structures
,
hashing
,
strings
1600
x9780
1326D2
Prefix-Suffix Palindrome (Hard version)
binary search
,
greedy
,
hashing
,
string suffix structures
,
strings
1800
x9508
1681D
Required Length
brute force
,
dfs and similar
,
dp
,
hashing
,
shortest paths
1700
x9252
1731C
Even Subarrays
bitmasks
,
brute force
,
hashing
,
math
,
number theory
1700
x8898
1500A
Going Home
brute force
,
hashing
,
implementation
,
math
1800
x8532
463C
Gargari and Bishops
greedy
,
hashing
,
implementation
1900
x8358
242C
King's Path
dfs and similar
,
graphs
,
hashing
,
shortest paths
1800
x7994
182D
Common Divisors
brute force
,
hashing
,
implementation
,
math
,
strings
1400
x7807
574B
Bear and Three Musketeers
brute force
,
dfs and similar
,
graphs
,
hashing
1500
x7599
1840E
Character Blocking
data structures
,
hashing
,
implementation
1600
x7494
1225D
Power Products
hashing
,
math
,
number theory
1800
x7369
1200E
Compress Words
brute force
,
hashing
,
implementation
,
string suffix structures
,
strings
2000
x6851
514C
Watto and Mechanism
binary search
,
data structures
,
hashing
,
string suffix structures
,
strings
2000
x6448
1470B
Strange Definition
bitmasks
,
graphs
,
hashing
,
math
,
number theory
1900
x6139
245H
Queries for Number of Palindromes
dp
,
hashing
,
strings
1800
x5926
1792D
Fixed Prefix Permutations
binary search
,
bitmasks
,
data structures
,
hashing
,
math
,
sortings
1700
x5863
1137B
Camp Schedule
greedy
,
hashing
,
strings
1600
x5828
1735D
Meta-set
brute force
,
combinatorics
,
data structures
,
hashing
,
math
1700
x5266
1537E2
Erase and Extend (Hard Version)
binary search
,
data structures
,
greedy
,
hashing
,
string suffix structures
,
strings
,
two pointers
2200
x4969
1228D
Complete Tripartite
brute force
,
constructive algorithms
,
graphs
,
hashing
,
implementation
1900
x4963
1214D
Treasure Island
dfs and similar
,
dp
,
flows
,
hashing
1900
x4930
1704D
Magical Array
constructive algorithms
,
hashing
,
implementation
,
math
1900
x4845
1493D
GCD of an Array
brute force
,
data structures
,
hashing
,
implementation
,
math
,
number theory
,
sortings
,
two pointers
2100
x4733
1574D
The Strongest Build
binary search
,
brute force
,
data structures
,
dfs and similar
,
graphs
,
greedy
,
hashing
,
implementation
2000
x4351
1109B
Sasha and One More Name
constructive algorithms
,
hashing
,
strings
1800
x4252
733D
Kostya the Sculptor
data structures
,
hashing
1600
x4130
1045I
Palindrome Pairs
hashing
,
strings
1600
x4066
1729F
Kirei and the Linear Function
hashing
,
math
1900
x3980
1624E
Masha-forgetful
brute force
,
constructive algorithms
,
dp
,
hashing
,
implementation
,
strings
2000
x3929
835D
Palindromic characteristics
brute force
,
dp
,
hashing
,
strings
1900
x3888
535D
Tavas and Malekas
greedy
,
hashing
,
string suffix structures
,
strings
1900
x3716
1800F
Dasha and Nightmares
bitmasks
,
hashing
,
meet-in-the-middle
,
strings
1900
x3672
1468F
Full Turn
geometry
,
hashing
,
number theory
1700
x3585
7D
Palindrome Degree
hashing
,
strings
2200
x3500
1950G
Shuffling Songs
bitmasks
,
dfs and similar
,
dp
,
graphs
,
hashing
,
implementation
,
strings
1900
x3288
1943B
Non-Palindromic Substring
hashing
,
implementation
,
math
,
strings
2000
x3155
1277D
Let's Play the Words?
data structures
,
hashing
,
implementation
,
math
1900
x2961
1284D
New Year and Conference
binary search
,
data structures
,
hashing
,
sortings
2100
x2911
1951E
No Palindromes
brute force
,
constructive algorithms
,
divide and conquer
,
greedy
,
hashing
,
implementation
,
math
,
strings
2000
x2885
1538E
Funny Substrings
data structures
,
hashing
,
implementation
,
matrices
,
strings
2100
x2799
39J
Spelling Check
hashing
,
implementation
,
strings
1500
x2784
113B
Petr#
brute force
,
data structures
,
hashing
,
strings
2000
x2712
154C
Double Profiles
graphs
,
hashing
,
sortings
2300
x2666
1671E
Preorder
combinatorics
,
divide and conquer
,
dp
,
dsu
,
hashing
,
sortings
,
trees
2100
x2640
633C
Spy Syndrome 2
data structures
,
dp
,
hashing
,
implementation
,
sortings
,
string suffix structures
,
strings
1900
x2605
633D
Fibonacci-ish
brute force
,
dp
,
hashing
,
implementation
,
math
2000
x2558
611D
New Year and Ancient Prophecy
dp
,
hashing
,
strings
2000
x2510
128B
String
brute force
,
constructive algorithms
,
hashing
,
implementation
,
string suffix structures
,
strings
2100
x2452
762C
Two strings
binary search
,
hashing
,
strings
,
two pointers
2100
x2358
757C
Felicity is Coming!
data structures
,
hashing
,
sortings
,
strings
1900
x2306
1476E
Pattern Matching
bitmasks
,
data structures
,
dfs and similar
,
graphs
,
hashing
,
sortings
,
strings
2300
x2240
533E
Correcting Mistakes
constructive algorithms
,
dp
,
greedy
,
hashing
,
strings
,
two pointers
1800
x2169
25E
Test
hashing
,
strings
2200
x2166
1322C
Instant Noodles
graphs
,
hashing
,
math
,
number theory
2300
x2120
724C
Ray Tracing
greedy
,
hashing
,
implementation
,
math
,
number theory
,
sortings
1800
x2105
526D
Om Nom and Necklace
hashing
,
string suffix structures
,
strings
2200
x2094
1729G
Cut Substrings
combinatorics
,
dp
,
hashing
,
strings
,
two pointers
2100
x2052
82B
Sets
constructive algorithms
,
hashing
,
implementation
1700
x2017
486E
LIS of Sequence
data structures
,
dp
,
greedy
,
hashing
,
math
2200
x2015
631D
Messenger
data structures
,
hashing
,
implementation
,
string suffix structures
,
strings
2100
x1984
1056E
Check Transcription
brute force
,
data structures
,
hashing
,
strings
2100
x1971
1223F
Stack Exterminable Arrays
data structures
,
divide and conquer
,
dp
,
hashing
2600
x1943
580E
Kefa and Watch
data structures
,
hashing
,
strings
2500
x1938
1257F
Make Them Similar
bitmasks
,
brute force
,
hashing
,
meet-in-the-middle
2400
x1927
1800G
Symmetree
dfs and similar
,
hashing
,
implementation
,
trees
2200
x1921
1469E
A Bit Similar
bitmasks
,
brute force
,
hashing
,
string suffix structures
,
strings
,
two pointers
2400
x1849
1721E
Prefix Function Queries
dfs and similar
,
dp
,
hashing
,
string suffix structures
,
strings
,
trees
2200
x1806
963D
Frequency of String
hashing
,
string suffix structures
,
strings
2500
x1800
1394B
Boboniu Walks on Graph
brute force
,
dfs and similar
,
graphs
,
hashing
2300
x1787
467D
Fedor and Essay
dfs and similar
,
dp
,
graphs
,
hashing
,
strings
2400
x1763
79C
Beaver
data structures
,
dp
,
greedy
,
hashing
,
strings
,
two pointers
1800
x1714
985F
Isomorphic Strings
hashing
,
strings
2300
x1694
710F
String Set Queries
brute force
,
data structures
,
hashing
,
interactive
,
string suffix structures
,
strings
2400
x1667
1494E
A-Z Graph
constructive algorithms
,
data structures
,
graphs
,
hashing
2400
x1652
567E
President and Roads
dfs and similar
,
graphs
,
hashing
,
shortest paths
2200
x1631
877F
Ann and Books
data structures
,
flows
,
hashing
2300
x1604
1887C
Minimum Array
binary search
,
brute force
,
constructive algorithms
,
data structures
,
greedy
,
hashing
,
two pointers
2400
x1563
1175F
The Number of Subpermutations
brute force
,
data structures
,
divide and conquer
,
hashing
,
math
2500
x1552
1634F
Fibonacci Additions
brute force
,
data structures
,
hashing
,
implementation
,
math
2700
x1524
1830C
Hyperregular Bracket Strings
combinatorics
,
greedy
,
hashing
,
math
,
number theory
,
sortings
2400
x1514
1746F
Kazaee
data structures
,
hashing
,
probabilities
2800
x1500
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