Chapter2-Typescript.ts

/**
 * Given a number n pairs of parentheses, generate all combinations of valid parentheses
Example 1:

Input: n = 3
Output: ["((()))","(()())","(())()","()(())","()()()"]

 * @param {number} n: Number of given parentheses
 * @return {string[]} result: Array that contains all valid parentheses
 * @see https://leetcode.com/problems/generate-parentheses/
 * 
 */

const generateParentheses = (n: number): string[] => {
    const result: string[] = []
  
    const solve = (
      chars: string,
      openParentheses: number,
      closedParentheses: number
    ) => {
      if (openParentheses === n && closedParentheses === n) {
        result.push(chars)
        return
      }
  
      if (openParentheses <= n) {
        solve(chars + '(', openParentheses + 1, closedParentheses)
      }
  
      if (closedParentheses < openParentheses) {
        solve(chars + ')', openParentheses, closedParentheses + 1)
      }
    }
  
    solve('', 0, 0)
  
    return result
  }
  
  console.log( generateParentheses(3))