Package g0701_0800.s0726_number_of_atoms

Class Solution

java.lang.Object
g0701_0800.s0726_number_of_atoms.Solution
public class Solution extends java.lang.Object
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.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    java.lang.String
    countOfAtoms(java.lang.String formula)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • countOfAtoms

      public java.lang.String countOfAtoms(java.lang.String formula)