# Minimum number of deletions and insertions to transform one string into another using C++.

C++Server Side ProgrammingProgramming

## Description

Given two strings str1 and str2 of size m and n respectively. The task is to delete and insert a minimum number of characters from/in str1 so as to transform it into str2.

Str1 = “tutorialspoint”
Str2 = “tutorials”
To transform str1 to str2 we have to delete five characters i.e.
“point” from str1.

## Algorithm

1. Find longest common subsequence of str1 and str2. Let’s call it as “lcsSize”
2. Number of characters to be deleted = (length of str1 - lcsSize)
3. Number of characters to be inserted = (length of str2 - lcsSize)

## Example

#include <iostream>
#include <algorithm>
using namespace std;
int lcs(string s1, string s2, int m, int n){
if (m == 0 || n == 0) {
return 0;
}
if (s1[m - 1] == s2[n - 1]) {
return 1 + lcs(s1, s2, m - 1, n - 1);
} else {
return max(lcs(s1, s2, m, n - 1), lcs(s1, s2, m - 1, n));
}
}
void minDeletionAndInsertion(string s1, string s2){
int m = s1.size();
int n = s2.size();
int lcsSize = lcs(s1, s2, m, n);
cout << "Min deletion = " << (m - lcsSize) << endl;
cout << "Min insertion = " << (n - lcsSize) << endl;
}
int main(){
minDeletionAndInsertion("tutorialspoint", "tutorials");
return 0;
}

## Output

When you compile and execute the above program. It generates the following output −

Min deletion = 5
Min insertion = 0