DIY: Find and Replace in a String

Solve the interview question "Find and Replace in a String" yourself in this lesson.

Problem statement

For this challenge, you will be given a string, s. Your task will be to perform replacement operations in this string that replace substrings with new ones and return the resultant string. For the replacements, you will be given an array of indices, an array of strings called sources, and an array of strings called targets.

The replacement should only take place if the sources[i] substring starts at the indices[i] position. The make the replacement, we have to replace sources[i] with targets[i] in the original string.

Note that the sources[i] and targets[i] substrings can have different lengths. Therefore, the resultant string can differ in length from the original string.


The function will take four arguments: a string called s, an array of integers called indices, an array of strings called sources, and another array of strings called targets. Let’s consider the following inputs:

s = "vmokgggqzp"
indices = [3,5,1]
sources = ["kg","ggq","mo"]
targets = ["s","so","bfr"]


The output of the function will be the string obtained after the replacements. The following is the output for the above-mentioned inputs:


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