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3 Longest Substring Without Repeating Characters
11 Container With Most Water
15 3Sum
16 3Sum Closest
18 4Sum
26 Remove Duplicates from Sorted Array
27 Remove Element
30 Substring with Concatenation of All Words
42 Trapping Rain Water
76 Minimum Window Substring
80 Remove Duplicates from Sorted Array II
88 Merge Sorted Array
125 Valid Palindrome
159 Longest Substring with At Most Two Distinct Characters
167 Two Sum II - Input array is sorted
202 Happy Number
209 Minimum Size Subarray Sum
259 3Sum Smaller
283 Move Zeroes
340 Longest Substring with At Most K Distinct Characters
344 Reverse String
345 Reverse Vowels of a String
349 Intersection of Two Arrays
350 Intersection of Two Arrays II
360 Sort Transformed Array
395 Longest Substring with At Least K Repeating Characters
424 Longest Repeating Character Replacement
438 Find All Anagrams in a String
487 Max Consecutive Ones II
524 Longest Word in Dictionary through Deleting
532 K-diff Pairs in an Array
567 Permutation in String
611 Valid Triangle Number
632 Smallest Range
713 Subarray Product Less Than K
723 Candy Crush
763 Partition Labels
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344 Reverse String
344.
Reverse String
1. Question
Write a function that takes a string as input and returns the string reversed.
Example:
Given s = "hello", return "olleh".
2. Implementation
(1) Two Pointers
1
class
Solution
{
2
public
String
reverseString
(
String
s
)
{
3
int
start
=
0
,
end
=
s
.
length
()
-
1
;
4
char
[]
letters
=
s
.
toCharArray
();
5
6
while
(
start
<
end
)
{
7
char
temp
=
letters
[
start
];
8
letters
[
start
]
=
letters
[
end
];
9
letters
[
end
]
=
temp
;
10
++
start
;
11
--
end
;
12
}
13
return
new
String
(
letters
);
14
}
15
}
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3. Time & Space Complexity
Two Pointers:
时间复杂度O(n), 空间复杂度O(1)
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Contents
344. Reverse String
1. Question
2. Implementation
3. Time & Space Complexity