1190 - Reverse Substrings Between Each Pair of Parentheses

 JAVA

• class Solution {
      public String reverseParentheses(String s) {
          int n = s.length();
          int[] d = new int[n];
          Deque<Integer> stk = new ArrayDeque<>();
          for (int i = 0; i < n; ++i) {
              if (s.charAt(i) == '(') {
                  stk.push(i);
              } else if (s.charAt(i) == ')') {
                  int j = stk.pop();
                  d[i] = j;
                  d[j] = i;
              }
          }
          StringBuilder ans = new StringBuilder();
          int i = 0, x = 1;
          while (i < n) {
              if (s.charAt(i) == '(' || s.charAt(i) == ')') {
                  i = d[i];
                  x = -x;
              } else {
                  ans.append(s.charAt(i));
              }
              i += x;
          }
          return ans.toString();
      }
  }

C++

• class Solution {
  public:
      string reverseParentheses(string s) {
          string stk;
          for (char& c : s) {
              if (c == ')') {
                  string t;
                  while (stk.back() != '(') {
                      t.push_back(stk.back());
                      stk.pop_back();
                  }
                  stk.pop_back();
                  stk += t;
              } else {
                  stk.push_back(c);
              }
          }
          return stk;
      }
  };
  

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