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# Check if it is possible to transform one string to another

Given two strings s1 and s2(all 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```

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 ` `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[``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() && ` `                        ``(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[``0``][``0``] ``=` `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

 ``

Output

`YES`

Time Complexity: O(N*M) where N and M are the lengths of the strings.
Auxiliary Space: O(N*M)

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