Check if it is possible to transform one string to another

• Difficulty Level : Hard
• Last Updated : 09 Sep, 2021

Given two strings s1 and s2(call letters in uppercase). Check if it is possible to convert s1 to s2 by performing following operations.

1. Make some lowercase letters uppercase.
2. Delete all the lowercase letters.

Examples:

Input : s1 = daBcd s2 = ABC
Output : yes
Explanation : daBcd -> dABCd -> ABC
Convert a and b at index 1 and 3 to
upper case, delete the rest those are
lowercase. We get the string s2.

Input : s1 = argaju    s2 = RAJ
Output : yes
Explanation : argaju -> aRgAJu -> RAJ
convert index 1, 3 and 4 to uppercase
and then delete. All lowercase letters

Input : s1 = ABcd s2= BCD
Output : NO

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

Approach:
Let DPi, j be 1 if it is possible to convert 1st i characters of s1 to j characters of s2, else DPi, j=0. Close observations gives us two conditions to deal with.
Initially DP0, 0=1, if DPi, j=1 then it is possible to check for next sets using following conditions.
1. If s1[i] in upper case is equal to s2[j] then it is possible to convert i+1 characters of s1 to j+1 characters of s2, hence DPi+1, j+1=1.
2. If s1[i] is in lower case, then it is possible to delete that element and hence i+1 characters can be converted to j characters of s2. Hence DPi+1, j=1.
If DPn, m=1, then it is possible to convert s1 to s2 by following conditions.

Below is the CPP illustration of the above approach.

C++

// cpp program to check if a string can
// be converted to another string by
// performing operations
#include <bits/stdc++.h>
using namespace std;

// function to check if a string can be
// converted to  another string by
// performing following operations
bool check(string s1, string s2)
{
// calculates length
int n = s1.length();
int m = s2.length();

bool dp[n + 1][m + 1];
for (int i = 0; i <= n; i++) {
for (int j = 0; j <= m; j++) {
dp[i][j] = false;
}
}
// mark 1st position as true
dp = true;

// traverse for all DPi, j
for (int i = 0; i < s1.length(); i++) {
for (int j = 0; j <= s2.length(); j++) {

// if possible for to convert i
// characters of s1 to j characters
// of s2
if (dp[i][j]) {

// if upper_case(s1[i])==s2[j]
// is same
if (j < s2.length() &&
(toupper(s1[i]) == s2[j]))
dp[i + 1][j + 1] = true;

// if not upper then deletion is
// possible
if (!isupper(s1[i]))
dp[i + 1][j] = true;
}
}
}

return (dp[n][m]);
}

// driver code
int main()
{
string s1 = "daBcd";
string s2 = "ABC";

if (check(s1, s2))
cout << "YES";
else
cout << "NO";

return 0;
}

Java

// Java program to check if a string can
// be converted to another string by
// performing operations
import java.io.*;

class GFG {

// function to check if a string can be
// converted to another string by
// performing following operations
static boolean check(String s1, String s2)
{
// calculates length
int n = s1.length();
int m = s2.length();

boolean dp[][]=new boolean[n + 1][m + 1];
for (int i = 0; i <= n; i++)
{
for (int j = 0; j <= m; j++)
{
dp[i][j] = false;
}
}
// mark 1st position as true
dp = true;

// traverse for all DPi, j
for (int i = 0; i < s1.length(); i++)
{
for (int j = 0; j <= s2.length(); j++)
{

// if possible for to convert i
// characters of s1 to j characters
// of s2
if (dp[i][j]) {

// if upper_case(s1[i])==s2[j]
// is same
if (j < s2.length() &&
(Character.toUpperCase(s1.charAt(i)) == s2.charAt(j)))
dp[i + 1][j + 1] = true;

// if not upper then deletion is
// possible
if (!Character.isUpperCase(s1.charAt(i)))
dp[i + 1][j] = true;
}
}
}

return (dp[n][m]);
}

// driver code
public static void main(String args[])
{
String s1 = "daBcd";
String s2 = "ABC";

if (check(s1, s2))
System.out.println("YES");
else
System.out.println("NO");

}
}

// This code is contributed by Nikita Tiwari.

Python3

# Python3 program to check if a string can
# be converted to another string by
# performing operations

# function to check if a string can be
# converted to another string by
# performing following operations
def check(s1,s2):

# calculates length
n = len(s1)
m = len(s2)
dp=([[False for i in range(m+1)]
for i in range(n+1)])

# mark 1st position as true
dp = True

# traverse for all DPi, j
for i in range(len(s1)):
for j in range(len(s2)+1):

# if possible for to convert i
# characters of s1 to j characters
# of s2
if (dp[i][j]):

# if upper_case(s1[i])==s2[j]
# is same
if ((j < len(s2) and
(s1[i].upper()== s2[j]))):
dp[i + 1][j + 1] = True

# if not upper then deletion is
# possible
if (s1[i].isupper()==False):
dp[i + 1][j] = True
return (dp[n][m])

# driver code
if __name__=='__main__':

s1 = "daBcd"
s2 = "ABC"
if (check(s1, s2)):
print("YES")
else:
print("NO")

# this code is contributed by
# sahilshelangia

C#

// C# program to check if a string can
// be converted to another string by
// performing operations
using System;

class GFG
{

// function to check if a string can be
// converted to another string by
// performing following operations
static bool check(string s1, string s2)
{
// calculates length
int n = s1.Length;
int m = s2.Length;

bool[,] dp = new bool[n + 1, m + 1];
for (int i = 0; i <= n; i++)
{
for (int j = 0; j <= m; j++)
{
dp[i, j] = false;
}
}

// mark 1st position as true
dp[0, 0] = true;

// traverse for all DPi, j
for (int i = 0; i < s1.Length; i++)
{
for (int j = 0; j <= s2.Length; j++)
{

// if possible for to convert i
// characters of s1 to j characters
// of s2
if (dp[i, j])
{

// if upper_case(s1[i])==s2[j]
// is same
if (j < s2.Length &&
(Char.ToUpper(s1[i]) == s2[j]))
dp[i + 1, j + 1] = true;

// if not upper then deletion is
// possible
if (!Char.IsUpper(s1[i]))
dp[i + 1, j] = true;
}
}
}

return (dp[n, m]);
}

// Driver Code
public static void Main()
{
string s1 = "daBcd";
string s2 = "ABC";

if (check(s1, s2))
Console.Write("YES");
else
Console.Write("NO");
}
}

// This code is contributed
// by ChitraNayal

Javascript

<script>
// Javascript program to check if a string can
// be converted to another string by
// performing operations

// function to check if a string can be
// converted to another string by
// performing following operations
function check(s1,s2)
{
// calculates length
let n = s1.length;
let m = s2.length;

let dp=new Array(n + 1);
for (let i = 0; i <= n; i++)
{
dp[i]=new Array(m+1);
for (let j = 0; j <= m; j++)
{
dp[i][j] = false;
}
}
// mark 1st position as true
dp = true;

// traverse for all DPi, j
for (let i = 0; i < s1.length; i++)
{
for (let j = 0; j <= s2.length; j++)
{

// if possible for to convert i
// characters of s1 to j characters
// of s2
if (dp[i][j]) {

// if upper_case(s1[i])==s2[j]
// is same
if (j < s2.length &&
(s1[i].toUpperCase() == s2[j]))
dp[i + 1][j + 1] = true;

// if not upper then deletion is
// possible

if (!(s1[i] == s1[i].toUpperCase()))
dp[i + 1][j] = true;
}
}
}

return (dp[n][m]);
}

// driver code
let s1 = "daBcd";
let s2 = "ABC";
if (check(s1, s2))
document.write("YES");
else
document.write("NO");

// This code is contributed by avanitrachhadiya2155
</script>

Output:

YES

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