Python: Find two indices making a given string unhappy

Last update on May 30 2025 11:50:22 (UTC/GMT +8 hours)

Indices for Unhappy String

A string is happy if every three consecutive characters are distinct. Write a Python program to find two indices associated with a given string being unhappy.

Input: 
Python
Output:
None

Input: 
Unhappy
Output:
[4, 5]

Input:
Find
Output:
None

Input:
Street
Output:
[3, 4]

Visual Presentation:

Sample Solution:

Python Code:

# License: https://bit.ly/3oLErEI

# Define a function named 'test' that takes a string 's' as input
def test(s):
    # Iterate through the characters of the string up to the second-to-last character
    for i in range(len(s) - 2):
        # Check if consecutive characters are the same, return the indices if true
        if s[i] == s[i + 1]:
            return [i, i + 1]
        # Check if characters with one character in between are the same, return the indices if true
        if s[i] == s[i + 2]:
            return [i, i + 2]

# Example 1
strs1 = "Python"
print("Original string:", strs1)
print("Find two indices making the string unhappy:")
print(test(strs1))

# Example 2
strs2 = "Unhappy"
print("\nOriginal string:", strs2)
print("Find two indices making the string unhappy:")
print(test(strs2))

# Example 3
strs3 = "Find"
print("\nOriginal string:", strs3)
print("Find two indices making the string unhappy:")
print(test(strs3))

# Example 4
strs4 = "Street"
print("\nOriginal string:", strs4)
print("Find two indices making the string unhappy:")
print(test(strs4))

Sample Output:

Original string: Python
Find two indices making the said string unhappy!
None

Original string: Unhappy
Find two indices making the said string unhappy!
[4, 5]

Original string: Find
Find two indices making the said string unhappy!
None

Original string: Street
Find two indices making the said string unhappy!
[3, 4]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to detect if any three consecutive characters in a string are not all distinct and return their indices.
• Write a Python program to slide a window of size 3 over a string and output the indices where duplicates occur.
• Write a Python program to use iteration and comparison to find the first occurrence of three characters with a duplicate, then return the indices of the violation.
• Write a Python program to implement a function that returns indices of the first “unhappy” triplet in a string or None if the string is happy.

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Python Code Editor :

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