Learn and practice the Sliding Window, and Union Find patterns to solve coding interview problems.

Speedrun the Oracle Coding Interview: Top Problems in Go

Each pattern in this module exemplifies the power of dissecting a problem in detail and figuring out the least expensive operations required to solve it. In the Sliding Window pattern, we’ll gain practice in various techniques to ensure that a solution that seems to require nested loops actually executes in linear time. Using the Union Find pattern, we’ll learn to solve a diverse set of problems using the disjoint-set data structure.

Elegant by Design

# Statement

Given a string, `str`, return the length of the longest substring without repeating characters.

**Constraints:**

* $1$ $\leq$ `str.length` $\leq 10^5$
* `str` consists of English letters, digits, and spaces.




# Examples


What should be the output if the following string is given as an input?


s = "conceptoftheday"


What should be the output if the following string is given as an input?
s = “conceptoftheday”

What should be the output if the following string is given as an input?


str = "bbbbbbbbbbbbbbbb"



What should be the output if the following string is given as an input?
str = “bbbbbbbbbbbbbbbb”

What should be the output if the following string is given as an input?

str = "racecar"


What should be the output if the following string is given as an input?
str = “racecar”

What should be the output if the following string is given as an input?


str = "bankrupted"



What should be the output if the following string is given as an input?
str = “bankrupted”

Longest Substring Without Repeating Characters

Longest Substring Without Repeating Characters

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.


Implement your solution in the following coding playground:

Help me debug only the function Longest Substring without Repeating Characters . . I don't need the corrected code.I don't want explanations or code review. Just provide me the exact and to-the-point error that helps me run the code successfully on the test cases provided.

Please help me understand why this code failed for the last failed test case. Don't give me the corrected code. . If yes, then Just provide me the exact and to-the-point error that helps me run the code successfully on the test cases provided.

Your current task is to review only the findLongestSubstring function and the other function(s) invoked in it/them. Do not review extra/helper files or functions not invoked in the solution function findLongestSubstring. Do not review the code of data structures objects instantiated like a binary tree, linked list, trie, union find, etc., in the solution functions. Just review the solution/algorithm function of the problem. Also, Answer the following questions: Is the Sliding Window pattern used? Take your time and review the code.

Please provide a brief time complexity analysis of the function findLongestSubstring. While calculating time complexity, include the time complexity of built-in Go functions invoked by the code. The Answer should be to the point and in a few lines.

Please provide a brief Space complexity analysis of the function findLongestSubstring. While calculating space complexity, include the space complexity of built-in Go functions invoked by the code. Do not include the space used for the input parameters and the space used for just returning an output(not used as a scratch space). The Answer should be to the point and in a few lines

def evaluate_results(self) -> object:
 """
 self.__inputs is the list of inputs that are passed as input to function
 self.__actual_output is a list of outputs that is produced by the learner's code
 return : self.__edu__result object
 """
 def find_longest_substring_eval(input_str):
 if len(input_str) == 0:
 return 0

 window_start, longest, window_length = 0, 0, 0

 last_seen_at = {}

 for index, val in enumerate(input_str):
 if val not in last_seen_at:
 last_seen_at[val] = index
 else:
 if last_seen_at[val] >= window_start:
 window_length = index - window_start
 if longest < window_length:
 longest = window_length
 window_start = last_seen_at[val] + 1

 last_seen_at[val] = index

 index += 1

 if longest < index - window_start:
 longest = index - window_start

 return longest

 
 # Expected output
 expected = find_longest_substring_eval(self.__inputs[0])

 # Actual output
 actual = self.__actual_outputs[0]

 # multiple outputs will be added at each index respectively for a single test_case
 expected_outputs = [] 

 # store the 1st expected output that should be displayed to the user 
 expected_outputs.append(expected)

 if json.dumps(expected) == json.dumps(actual):
 self.__edu_result.store_result(expected_outputs, TestCaseResult.PASS)
 else:
 self.__edu_result.store_result(expected_outputs, TestCaseResult.FAIL)

 return self.__edu_result

package main

func findLongestSubstring(str string) int {
	
	// Replace this placeholder return statement with your code
	
	return -1
}



PrivateTestCases.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1: "abcdbea"
    output: 
    - 1: 5
  - name: "testcase 2"
    inputs:
    - 1: "aba"
    output:
    - 1 : 2
  - name: "testcase 3"
    inputs:
    - 1: "abccabcabcc"
    output:
    - 1: 3
  - name: "testcase 4"
    inputs:
    - 1: "aaaabaaa"
    output:
    - 1: 2
  - name: "testcase 5"
    inputs:
    - 1: "bbbbb"
    output:
    - 1: 1

def sum(input_1, input_2):
    return input_1+input_2

def validate_inputs(self) -> None:
 """
 self.__inputs is the list of inputs that are passed as input to function
 store the result using the self.store_result(error_msg, status)
 return : void
 """
 input_str = self.__inputs[0]
 lower_bound = 1
 upper_bound = 10**5

 # inputs can be accessed using self.__inputs starting from 0 to len(self.__inputs) - 1
 if len(input_str) < lower_bound or len(input_str) > upper_bound:
 self.store_result ("expected 'input_str' to have " + str(lower_bound) + " <= size <= " + str(upper_bound) + " but got " + str(len(input_str)) , ValidationFunction.FAIL)

 else:
 self.store_result("", ValidationFunction.PASS)

Try to solve the Longest Substring without Repeating Characters problem.


Longest Substring without Repeating Characters

Try to solve the Longest Substring without Repeating Characters problem.

Sliding Window

Union Find

Conclusion

Longest Substring without Repeating Characters

Statement

Examples

Understand the problem

Figure it out!

Try it yourself