Class Solution

  • All Implemented Interfaces:

    
    public final class Solution
    
                        

    726 - Number of Atoms\.

    Hard

    Given a string formula representing a chemical formula, return the count of each atom.

    The atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name.

    One or more digits representing that element's count may follow if the count is greater than 1. If the count is 1, no digits will follow.

    • For example, "H2O" and "H2O2" are possible, but "H1O2" is impossible.

    Two formulas are concatenated together to produce another formula.

    • For example, "H2O2He3Mg4" is also a formula.

    A formula placed in parentheses, and a count (optionally added) is also a formula.

    • For example, "(H2O2)" and "(H2O2)3" are formulas.

    Return the count of all elements as a string in the following form: the first name (in sorted order), followed by its count (if that count is more than 1), followed by the second name (in sorted order), followed by its count (if that count is more than 1), and so on.

    The test cases are generated so that all the values in the output fit in a 32-bit integer.

    Example 1:

    Input: formula = "H2O"

    Output: "H2O"

    Explanation: The count of elements are {'H': 2, 'O': 1}.

    Example 2:

    Input: formula = "Mg(OH)2"

    Output: "H2MgO2"

    Explanation: The count of elements are {'H': 2, 'Mg': 1, 'O': 2}.

    Example 3:

    Input: formula = "K4(ON(SO3)2)2"

    Output: "K4N2O14S4"

    Explanation: The count of elements are {'K': 4, 'N': 2, 'O': 14, 'S': 4}.

    Constraints:

    • 1 <= formula.length <= 1000

    • formula consists of English letters, digits, '(', and ')'.

    • formula is always valid.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      public final class Solution.Item
    • Field Summary

      Fields 
      Modifier and Type Field Description
    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()
    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description
    • Method Summary

      Modifier and Type Method Description
      final String countOfAtoms(String formula)
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait