Find triplets with zero sum (3Sum Problem). Given an array of integers, write a code to find all unique triplets in the array which gives the sum of zero.
Note: The solution set must not contain duplicate triplets.
For example –
Example 1:
Input: {-1, 0, 1, 2, -1, -4}
Output: {-1, 0, 1}, {-1, -1, 2}
Example 2:
Input: {-8, -7, 5, 2}
Output: {-7, 5, 2}
Given a string s, find the length of the longest substring without repeating characters.
For example –
Example 1:
Input: “abcabcbb” Output: 3
The output string is “abc”, with a length of 3.
Example 2:
Input: “bbbbb” Output: 1
The longest substring in this example is “b”. Its length is 1.
Example 3:
Input: “pwwkew” Output: 3
The answer is “wke”. Its length is 3.
In this tutorial, I am going to discuss a very interesting problem sort characters by frequency.
Given a string, write a method to sort it in decreasing order based on the frequency of characters.
For example:
Example 1
Input : “teee”
Output: “eeet”
Example 2:
Input: “dddbbb”
Output: “dddbbb” or “bbbddd” (Both d and b appear 3 times so any of the above output are valid)
Example 3:
Input: “Eett”
Output: “ttEe” or “tteE” (Both e and E are two different characters so the output should not be “Eett”)