Last Substring in Lexicographical Order in C++

Suppose we have s as string, we have to find the last substring of s in lexicographic order.

So, if the input is like "abbbcabbc", then the output will be "cabbc"

To solve this, we will follow these steps −

• i := 0,j := 1,k := 0

• while j + k < size of s, do &minsu;

  • if s[i + k] is same as s[j + k], then −

    • (increase k by 1)

    • Ignore following part, skip to the next iteration

  • if s[i + k] < s[j + k], then −

    • i := j

    • (increase j by 1)

  • Otherwise

    • j := j + k + 1

  • k := 0

return substring of s from index i to end

Let us see the following implementation to get better understanding −

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
class Solution {
   public:
   string lastSubstring(string s) {
      int i = 0;
      int j = 1;
      int k = 0;
      while(j + k < s.size()){
         if(s[i + k] == s[j + k]) {
            k++;
            continue;
         }
         if(s[i + k] < s[j + k]){
            i = j;
            j++;
         }else{
            j = j + k + 1;
         }
         k = 0;
      }
      return s.substr(i, s.size() - i);
   }
};
main(){
   Solution ob;
   cout << (ob.lastSubstring("abbbcabbc"));
}

Input

"abbbcabbc"

Output

cabbc