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Before contest
Codeforces Round #851 (Div. 2)
38:22:24
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Difficulty:
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dfs and similar
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
1792E
Divisors and Table
brute force
,
dfs and similar
,
dp
,
number theory
2400
x751
1790G
Tokens on Graph
constructive algorithms
,
dfs and similar
,
graphs
,
shortest paths
2300
x588
1790F
Timofey and Black-White Tree
brute force
,
dfs and similar
,
divide and conquer
,
graphs
,
greedy
,
math
,
shortest paths
,
trees
2100
x1814
1787D
Game on Axis
combinatorics
,
dfs and similar
,
dsu
,
graphs
,
implementation
1900
x2259
1783F
Double Sort II
dfs and similar
,
flows
,
graph matchings
,
graphs
2500
x583
1778F
Maximizing Root
dfs and similar
,
dp
,
graphs
,
math
,
number theory
,
trees
x288
1778E
The Tree Has Fallen!
bitmasks
,
dfs and similar
,
math
,
trees
x485
1777E
Edge Reverse
binary search
,
dfs and similar
,
graphs
,
trees
x989
1777D
Score of a Tree
bitmasks
,
combinatorics
,
dfs and similar
,
dp
,
math
,
probabilities
,
trees
x1984
1775D
Friendly Spiders
dfs and similar
,
graphs
,
math
,
number theory
,
shortest paths
1800
x3706
1774E
Two Chess Pieces
dfs and similar
,
dp
,
greedy
,
trees
1900
x2472
1772F
Copy of a Copy of a Copy
constructive algorithms
,
dfs and similar
,
graphs
,
implementation
,
sortings
2000
x1470
1771D
Hossam and (sub-)palindromic tree
brute force
,
data structures
,
dfs and similar
,
dp
,
strings
,
trees
2100
x1903
1770E
Koxia and Tree
combinatorics
,
dfs and similar
,
dp
,
dsu
,
math
,
probabilities
,
trees
2400
x1035
1770D
Koxia and Game
constructive algorithms
,
data structures
,
dfs and similar
,
dsu
,
flows
,
games
,
graph matchings
,
graphs
,
implementation
2000
x2921
1768D
Lucky Permutation
constructive algorithms
,
dfs and similar
,
graphs
,
greedy
1800
x4902
1764F
Doremy's Experimental Tree
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
sortings
,
trees
2500
x691
1763F
Edge Queries
data structures
,
dfs and similar
,
dp
,
dsu
,
graphs
,
trees
3000
x233
1761C
Set Construction
constructive algorithms
,
dfs and similar
,
graphs
,
greedy
1400
x6909
1760G
SlavicG's Favorite Problem
bitmasks
,
dfs and similar
,
graphs
1700
x4733
1758E
Tick, Tock
combinatorics
,
dfs and similar
,
dsu
,
graphs
2500
x593
1753D
The Beach
constructive algorithms
,
dfs and similar
,
graphs
,
shortest paths
2400
x1200
1749F
Distance to the Path
data structures
,
dfs and similar
,
trees
2800
x362
1749E
Cactus Wall
constructive algorithms
,
dfs and similar
,
graphs
,
shortest paths
2400
x1224
1746D
Paths on the Tree
dfs and similar
,
dp
,
greedy
,
sortings
,
trees
1900
x3685
1741G
Kirill and Company
bitmasks
,
brute force
,
dfs and similar
,
dp
,
flows
,
graphs
,
shortest paths
2200
x1072
1741D
Masha and a Beautiful Tree
dfs and similar
,
divide and conquer
,
graphs
,
sortings
,
trees
1300
x10827
1740E
Hanging Hearts
constructive algorithms
,
data structures
,
dfs and similar
,
dp
,
greedy
,
trees
1800
x3140
1739D
Reset K Edges
binary search
,
data structures
,
dfs and similar
,
graphs
,
greedy
,
trees
1900
x3789
1738D
Permutation Addicts
constructive algorithms
,
data structures
,
dfs and similar
,
dsu
,
graphs
,
trees
1900
x2807
1735C
Phase Shift
dfs and similar
,
dsu
,
graphs
,
greedy
,
implementation
,
strings
1400
x7884
1726D
Edge Split
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
,
probabilities
,
trees
2000
x2994
1722F
L-shapes
dfs and similar
,
implementation
1700
x5128
1721F
Matching Reduction
brute force
,
constructive algorithms
,
dfs and similar
,
flows
,
graph matchings
,
graphs
,
interactive
2800
x275
1721E
Prefix Function Queries
dfs and similar
,
dp
,
hashing
,
string suffix structures
,
strings
,
trees
2200
x1448
1721D
Maximum AND
bitmasks
,
dfs and similar
,
divide and conquer
,
greedy
,
sortings
1800
x4955
1716E
Swap and Maximum Block
bitmasks
,
data structures
,
dfs and similar
,
divide and conquer
,
dp
2500
x815
1714G
Path Prefixes
binary search
,
data structures
,
dfs and similar
,
trees
1700
x5463
1712F
Triameter
binary search
,
data structures
,
dfs and similar
,
trees
3200
x187
1709E
XOR Tree
bitmasks
,
data structures
,
dfs and similar
,
dsu
,
greedy
,
trees
2400
x1674
1707D
Partial Virtual Trees
combinatorics
,
dfs and similar
,
dp
,
math
,
trees
3000
x418
1707C
DFS Trees
dfs and similar
,
dsu
,
graphs
,
greedy
,
sortings
,
trees
2400
x1107
1706E
Qpwoeirut and Vertices
binary search
,
data structures
,
dfs and similar
,
divide and conquer
,
dsu
,
greedy
,
trees
2300
x1790
1702G2
Passable Paths (hard version)
data structures
,
dfs and similar
,
trees
2000
x3243
1702G1
Passable Paths (easy version)
dfs and similar
,
trees
1900
x3992
1702E
Split Into Two Sets
dfs and similar
,
dsu
,
graphs
1600
x9250
1696F
Tree Recovery
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
,
trees
2600
x724
1695E
Ambiguous Dominoes
constructive algorithms
,
dfs and similar
,
graphs
2700
x355
1695D2
Tree Queries (Hard Version)
constructive algorithms
,
dfs and similar
,
dp
,
greedy
,
trees
2300
x1584
1695D1
Tree Queries (Easy Version)
brute force
,
constructive algorithms
,
dfs and similar
,
dp
,
greedy
,
trees
2200
x1741
1693B
Fake Plastic Trees
dfs and similar
,
dp
,
greedy
,
trees
1700
x6579
1691F
K-Set Tree
combinatorics
,
dfs and similar
,
dp
,
math
,
trees
2500
x743
1691E
Number of Groups
data structures
,
dfs and similar
,
dsu
,
graphs
,
greedy
,
sortings
2300
x1466
1689E
ANDfinity
bitmasks
,
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
2500
x966
1689C
Infected Tree
dfs and similar
,
dp
,
trees
1600
x8105
1685D1
Permutation Weight (Easy Version)
constructive algorithms
,
dfs and similar
,
dsu
2800
x341
1684H
Hard Cut
constructive algorithms
,
dfs and similar
,
divide and conquer
,
math
3400
x180
1682E
Unordered Swaps
constructive algorithms
,
dfs and similar
,
graphs
,
greedy
,
math
,
sortings
,
trees
2700
x442
1681F
Unique Occurrences
data structures
,
dfs and similar
,
divide and conquer
,
dp
,
dsu
,
trees
2300
x1099
1681D
Required Length
brute force
,
dfs and similar
,
dp
,
hashing
,
shortest paths
1700
x7595
1680F
Lenient Vertex Cover
dfs and similar
,
divide and conquer
,
dsu
,
graphs
,
trees
2600
x390
1679D
Toss a Coin to Your Graph...
binary search
,
dfs and similar
,
dp
,
graphs
1900
x3618
1677C
Tokitsukaze and Two Colorful Tapes
constructive algorithms
,
dfs and similar
,
graphs
,
greedy
1900
x2766
1676G
White-Black Balanced Subtrees
dfs and similar
,
dp
,
graphs
,
trees
1300
x10461
1675F
Vlad and Unfinished Business
dfs and similar
,
dp
,
greedy
,
trees
1800
x3915
1674G
Remove Directed Edges
dfs and similar
,
dp
,
graphs
2000
x1948
1672F2
Checker for Array Shuffling
constructive algorithms
,
dfs and similar
,
graphs
2800
x635
1670E
Hemose on the Tree
bitmasks
,
constructive algorithms
,
dfs and similar
,
trees
2200
x1415
1670C
Where is the Pizza?
data structures
,
dfs and similar
,
dsu
,
graphs
,
implementation
,
math
1400
x7929
1669G
Fall Down
dfs and similar
,
implementation
1200
x13667
1667D
Edge Elimination
constructive algorithms
,
dfs and similar
,
dp
,
trees
2900
x456
1666L
Labyrinth
dfs and similar
,
graphs
1800
x2466
1662O
Circular Maze
brute force
,
dfs and similar
,
graphs
,
implementation
x915
1662F
Antennas
data structures
,
dfs and similar
,
graphs
,
graphs
,
implementation
,
implementation
,
shortest paths
,
shortest paths
x677
1661B
Getting Zero
bitmasks
,
brute force
,
dfs and similar
,
dp
,
graphs
,
greedy
,
shortest paths
1300
x14010
1659F
Tree and Permutation Game
dfs and similar
,
games
,
graphs
,
trees
3000
x141
1659E
AND-MEX Walk
bitmasks
,
brute force
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
2200
x1175
1657F
Words on Tree
2-sat
,
dfs and similar
,
dsu
,
graphs
,
trees
2600
x424
1656E
Equal Tree Sums
constructive algorithms
,
dfs and similar
,
math
,
trees
2200
x2770
1654G
Snowy Mountain
data structures
,
dfs and similar
,
graphs
,
greedy
,
shortest paths
,
trees
2900
x277
1654D
Potion Brewing Class
dfs and similar
,
math
,
number theory
,
trees
2100
x2479
1651E
Sum of Matchings
brute force
,
combinatorics
,
constructive algorithms
,
dfs and similar
,
graph matchings
,
greedy
,
math
2600
x403
1651D
Nearest Excluded Points
binary search
,
data structures
,
dfs and similar
,
graphs
,
shortest paths
1900
x4098
1650G
Counting Shortcuts
data structures
,
dfs and similar
,
dp
,
graphs
,
shortest paths
2100
x1971
1648F
Two Avenues
data structures
,
dfs and similar
,
graphs
3500
x49
1648E
Air Reform
data structures
,
dfs and similar
,
divide and conquer
,
dsu
,
graphs
,
implementation
,
trees
3200
x274
1647E
Madoka and the Sixth-graders
data structures
,
dfs and similar
,
greedy
2500
x824
1646D
Weight the Tree
constructive algorithms
,
dfs and similar
,
dp
,
implementation
,
trees
2000
x2896
1637F
Towers
constructive algorithms
,
dfs and similar
,
dp
,
greedy
,
trees
2500
x1399
1635E
Cars
2-sat
,
constructive algorithms
,
dfs and similar
,
dsu
,
graphs
,
greedy
,
sortings
2200
x1837
1634E
Fair Share
constructive algorithms
,
data structures
,
dfs and similar
,
graph matchings
,
graphs
2400
x1338
1633E
Spanning Tree Queries
binary search
,
data structures
,
dfs and similar
,
dsu
,
graphs
,
greedy
,
math
,
sortings
,
trees
2400
x1255
1632E2
Distance Tree (hard version)
binary search
,
dfs and similar
,
shortest paths
,
trees
2700
x739
1632E1
Distance Tree (easy version)
binary search
,
data structures
,
dfs and similar
,
graphs
,
shortest paths
,
trees
2400
x923
1627C
Not Assigning
constructive algorithms
,
dfs and similar
,
number theory
,
trees
1400
x11950
1626E
Black and White Tree
dfs and similar
,
greedy
,
trees
2400
x1220
1625E2
Cats on the Upgrade (hard version)
binary search
,
data structures
,
dfs and similar
,
graphs
,
trees
2800
x456
1625E1
Cats on the Upgrade (easy version)
brute force
,
data structures
,
dfs and similar
,
divide and conquer
,
dp
,
graphs
,
trees
2500
x815
1624G
MinOr Tree
bitmasks
,
dfs and similar
,
dsu
,
graphs
,
greedy
1900
x4486
1623E
Middle Duplication
data structures
,
dfs and similar
,
greedy
,
strings
,
trees
2500
x930
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