Given two strings, find if first string is a subsequence of second

// Recursive C++ program to check if a string is subsequence of another string
#include<iostream>
#include<cstring>
using namespace std;

// Returns true if str1[] is a subsequence of str2[]. m is
// length of str1 and n is length of str2
bool isSubSequence(char str1[], char str2[], int m, int n)
{
    // Base Cases
    if (m == 0) return true;
    if (n == 0) return false;

    // If last characters of two strings are matching
    if (str1[m-1] == str2[n-1])
        return isSubSequence(str1, str2, m-1, n-1);

    // If last characters are not matching
    return isSubSequence(str1, str2, m, n-1);
}

// Driver program to test methods of graph class
int main()
{
    char str1[] = "gksrek";
    char str2[] = "geeksforgeeks";
    int m = strlen(str1);
    int n = strlen(str2);
    isSubSequence(str1, str2, m, n)? cout << "Yes ":
                                     cout << "No";
    return 0;
}

// Recursive Java program to check if a string
// is subsequence of another string
import java.io.*;

class SubSequence
{
	// Returns true if str1[] is a subsequence of str2[]
	// m is length of str1 and n is length of str2
	static boolean isSubSequence(String str1, String str2, int m, int n)
	{
		// Base Cases
		if (m == 0) 
			return true;
		if (n == 0) 
			return false;
			
		// If last characters of two strings are matching
		if (str1.charAt(m-1) == str2.charAt(n-1))
			return isSubSequence(str1, str2, m-1, n-1);

		// If last characters are not matching
		return isSubSequence(str1, str2, m, n-1);
	}
	
	// Driver program
	public static void main (String[] args) 
	{
		String str1 = "gksrek";
		String str2 = "geeksforgeeks";
		int m = str1.length();
		int n = str2.length();
		boolean res = isSubSequence(str1, str2, m, n);
		if(res)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
}

// Contributed by Pramod Kumar

# Recursive Python program to check if a string is subsequence
# of another string

# Returns true if str1[] is a subsequence of str2[]. m is
# length of str1 and n is length of str2
def isSubSequence(string1, string2, m, n):
    # Base Cases
    if m == 0:    return True
    if n == 0:    return False

    # If last characters of two strings are matching
    if string1[m-1] == string2[n-1]:
        return isSubSequence(string1, string2, m-1, n-1)

    # If last characters are not matching
    return isSubSequence(string1, string2, m, n-1)

# Driver program to test the above function
string1 = "gksrek"
string2 = "geeksforgeeks"
m = len(string1)
n = len(string2)
if isSubSequence(string1, string2, m, n):
    print "Yes"
else:
    print "No"

# This code is contributed by BHAVYA JAIN

// Iterative C++ program to check if a string is subsequence of another string
#include<iostream>
#include<cstring>
using namespace std;

// Returns true if str1[] is a subsequence of str2[]. m is
// length of str1 and n is length of str2
bool isSubSequence(char str1[], char str2[], int m, int n)
{
   int j = 0; // For index of str1 (or subsequence

   // Traverse str2 and str1, and compare current character 
   // of str2 with first unmatched char of str1, if matched 
   // then move ahead in str1
   for (int i=0; i<n&&j<m; i++)
       if (str1[j] == str2[i])
         j++;

   // If all characters of str1 were found in str2
   return (j==m);
}

// Driver program to test methods of graph class
int main()
{
    char str1[] = "gksrek";
    char str2[] = "geeksforgeeks";
    int m = strlen(str1);
    int n = strlen(str2);
    isSubSequence(str1, str2, m, n)? cout << "Yes ":
                                     cout << "No";
    return 0;
}

// Iterative Java program to check if a string is subsequence of another string
import java.io.*;

class SubSequence 
{
	// Returns true if str1[] is a subsequence of str2[]
	// m is length of str1 and n is length of str2
	static boolean isSubSequence(String str1, String str2, int m, int n)
	{
		int j = 0;
		
		// Traverse str2 and str1, and compare current character 
		// of str2 with first unmatched char of str1, if matched 
		// then move ahead in str1
		for (int i=0; i<n&&j<m; i++)
			if (str1.charAt(j) == str2.charAt(i))
				j++;

		// If all characters of str1 were found in str2
		return (j==m); 
	}
	
        // Driver program to test methods of graph class
        public static void main (String[] args) 
	{
		String str1 = "gksrek";
		String str2 = "geeksforgeeks";
		int m = str1.length();
		int n = str2.length();
		boolean res = isSubSequence(str1, str2, m, n);
		if(res)
			System.out.println("Yes");
		else
			System.out.println("No");
	}
}

// Contributed by Pramod Kumar

# Iterative Python program to check if a string is subsequence of another string

# Returns true if str1 is a subsequence of str2
# m is length of str1, n is length of str2
def isSubSequence(str1,str2,m,n):
	
	j = 0	# Index of str1
	i = 0	# Index of str2
	
	# Traverse both str1 and str2
	# Compare current character of str2 with 
	# first unmatched character of str1
	# If matched, then move ahead in str1
	
	while j<m and i<n:
		if str1[j] == str2[i]:	
			j = j+1	
		i = i + 1
		
	# If all characters of str1 matched, then j is equal to m
	return j==m
	
# Driver Program

str1 = "gksrek"
str2 = "geeksforgeeks"
m = len(str1)
n = len(str2)

print "Yes" if isSubSequence(str1,str2,m,n) else "No"

# Contributed by Harshit Agrawal