LeetCode 2480: Form a Chemical Bond

Explanation:

To solve this problem, we can iterate through the given chemical formula and count the number of atoms for each element. We need to form a chemical bond by combining the elements in a specific order based on their counts. We will maintain a hashmap to store the element counts and then generate the chemical bond string accordingly.

Algorithm:

1. Initialize an empty hashmap elementCounts to store the counts of each element.
2. Iterate through the chemical formula and update the counts of each element in the elementCounts hashmap.
3. Initialize an empty string chemicalBond to store the final chemical bond.
4. Iterate through the elements in a specific order (e.g., alphabetical order) and append the element name and its count to the chemicalBond string.
5. Return the chemicalBond string as the result.

Time Complexity:

The time complexity of this algorithm is O(n), where n is the length of the chemical formula string.

Space Complexity:

The space complexity of this algorithm is O(m), where m is the number of unique elements in the chemical formula.

:

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public String formChemicalBond(String formula) {
    Map<Character, Integer> elementCounts = new HashMap<>();
    
    for (char c : formula.toCharArray()) {
        elementCounts.put(c, elementCounts.getOrDefault(c, 0) + 1);
    }
    
    StringBuilder chemicalBond = new StringBuilder();
    Map<Character, Integer> sortedElementCounts = new TreeMap<>(elementCounts);
    
    for (Map.Entry<Character, Integer> entry : sortedElementCounts.entrySet()) {
        chemicalBond.append(entry.getKey()).append(entry.getValue());
    }
    
    return chemicalBond.toString();
}