Sort an Array of Version Numbers

Given an array of strings arr[], consisting of N strings each representing dot separated numbers in the form of software versions.

Input: arr[] = {“1.1.2”, “0.9.1”, “1.1.0”}
Output: “0.9.1” “1.1.0” “1.1.2”

Input: arr[] = {“1.2”, “0.8.1”, “1.0”}
Output: “0.8.1” “1.0” “1.2”

Approach: Follow the steps below to solve the problem:

• Create a function to compare two strings.
• Store strings into a vector.
• In order to compare two dot separated strings S1 and S2, iterate up to the length min(S1, S2) + 1 and compare each numerical parts of the string and sort accordingly.
• Repeat the above steps for each pair of string and sort the array accordingly.

  Below is the implementation of above idea:

  C++

  // C++ Program to implement
  // the above approach
  #include <bits/stdc++.h>
  using namespace std;
  
  // Compares two strings
  int check(const string& a, const string& b)
  {
  
      int al = a.length();
      int bl = b.length();
  
      int i = 0, j = 0;
      while (i < al && j < bl) {
          if (a[i] == b[j]) {
              ++i;
              ++j;
          }
          else if (a[i] > b[j]) {
              return 1;
          }
          else
              return -1;
      }
  
      if (i == al && j == bl)
          return 0;
      if (i == al)
          return -1;
      return 1;
  }
  
  // Function to split strings based on dots
  vector<string> getTokens(const string& a)
  {
      vector<string> v;
      string s;
  
      // Stringstream is used here for
      // tokenising the string based
      // on "." delimiter which might
      // contain unequal number of "."[dots]
      stringstream ss(a);
      while (getline(ss, s, '.')) {
          v.push_back(s);
      }
      return v;
  }
  
  // Comparator to sort the array of strings
  bool comp(const string& a, const string& b)
  {
  
      // Stores the numerical substrings
      vector<string> va, vb;
      va = getTokens(a);
      vb = getTokens(b);
  
      // Iterate up to length of minimum
      // of the two strings
      for (int i = 0; i < min(va.size(), vb.size());
           i++) {
  
          // Compare each numerical substring
          // of the two strings
          int countCheck = check(va[i], vb[i]);
  
          if (countCheck == -1)
              return true;
  
          else if (countCheck == 1)
              return false;
      }
  
      if (va.size() < vb.size())
          return true;
  
      return false;
  }
  
  // Driver Code
  int main()
  {
  
      vector<string> s;
      s.push_back("1.1.0");
      s.push_back("1.2.1");
      s.push_back("0.9.1");
      s.push_back("1.3.4");
      s.push_back("1.1.2");
      s.push_back("1.1.2.2.3");
      s.push_back("9.3");
  
      // Sort the strings using comparator
      sort(s.begin(), s.end(), comp);
  
      // Display the sorted order
      for (int i = 0; i < s.size(); i++) {
          cout << s[i] << endl;
      }
      cout << endl;
      return 0;
  }
  Output:

  0.9.1
  1.1.0
  1.1.2
  1.1.2.2.3
  1.2.1
  1.3.4
  9.3
  

  Time Complexity: O(N*L*logN), where N is the total number of version strings, L is the maximum length among those strings.
  Auxilairy Space: O(N * L)