Tags: #◇Computer Science #◇CSALGCM #◇Algorithms and Complexity #◇HackerRank #◇Fool Arcana #◇Strings

CamelCase

◇Problem Description

Given a camelCase string, determine how many words it contains.

A camelCase string is a single string formed by concatenating multiple words where the first letter of each word after the first is capitalized. The first word is always lowercase.

Input Format:

• A single camelCase string s.

Output Format:

• A single integer: the number of words.

Constraints: $1 \leq \text{len}(s) \leq 10^5$

Sample:

◇Approach & Intuition

The key property of camelCase is that every uppercase letter signals the start of a new word. The first word has no leading uppercase letter, so we account for it by starting the count at 1.

Then we simply scan the string character by character and increment the counter every time we encounter an uppercase letter.

Mental model: Think of an uppercase letter as a "word separator" embedded inside the string rather than being a separate whitespace character.

[!tip] Pattern Recognition
This is a linear scan with a counter pattern — one of the most common patterns in string problems. Recognize it: you only care about one specific property of each character, you never need to look ahead or behind.

◇Complexity Analysis

◇Original Stub (HackerRank Template)

#include <bits/stdc++.h>

using namespace std;

/*
 * Complete the 'camelcase' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts STRING s as parameter.
 */

int camelcase(string s) {

}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string s;
    getline(cin, s);

    int result = camelcase(s);

    fout << result << "\n";

    fout.close();

    return 0;
}

◇Full Solution

#include <bits/stdc++.h>

using namespace std;

/*
 * Complete the 'camelcase' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts STRING s as parameter.
 */

int camelcase(string s) {
    // Each uppercase letter marks the start of a new word.
    // The first word has no leading uppercase, so start count at 1.
    int count = 1;
    for (char c : s) {
        if (isupper(c)) count++;
    }
    return count;
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string s;
    getline(cin, s);

    int result = camelcase(s);

    fout << result << "\n";

    fout.close();

    return 0;
}

◇References & Navigation

• Related Notes: ◇Computational Thinking in Problem Solving
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