C++ Program to Implement Levenshtein Distance Computing Algorithm

The Levenshtein distance between two strings means the minimum number of edits needed to transform one string into the other, with the edit operations i.e; insertion, deletion, or substitution of a single character.

For example: The Levenshtein Distance between cat and mat is 1 −

cat mat(substitution of ‘c’ with ‘m’)

Here is a C++ Program to implement Levenshtein Distance computing algorithm.

Algorithms

Begin
   Take the strings as input and also find their length.
   For i = 0 to l1
      dist[0][i] = i
   For j = 0 to l2
      dist[j][0] = j
   For j=1 to l1
      For i=1 to l2
         if(s1[i-1] == s2[j-1])
            track= 0
         else
            track = 1
         done
         t = MIN((dist[i-1][j]+1),(dist[i][j-1]+1))
         dist[i][j] = MIN(t,(dist[i-1][j-1]+track))
      Done
   Done
   Print the Levinstein distance: dist[l2][l1]
End

Example

#include <iostream>
#include <math.h>
#include <string.h>
using namespace std;
#define MIN(x,y) ((x) < (y) ? (x) : (y)) //calculate minimum between two values
int main() {
   int i,j,l1,l2,t,track;
   int dist[50][50];
   //take the strings as input
   char s1[] = "tutorials";
   char s2[] = "point";
   //stores the lenght of strings s1 and s2
   l1 = strlen(s1);
   l2= strlen(s2);
   for(i=0;i<=l1;i++) {
      dist[0][i] = i;
   }
   for(j=0;j<=l2;j++) {
      dist[j][0] = j;
   }
   for (j=1;j<=l1;j++) {
      for(i=1;i<=l2;i++) {
         if(s1[i-1] == s2[j-1]) {
            track= 0;
         } else {
            track = 1;
         }
         t = MIN((dist[i-1][j]+1),(dist[i][j-1]+1));
         dist[i][j] = MIN(t,(dist[i-1][j-1]+track));
      }
   }
   cout<<"The Levinstein distance is:"<<dist[l2][l1];
   return 0;
}

Output

The Levinstein distance is:8