Added Is_Subsequence.cpp file

Author: Anish0203

C++/Algorithms/Greedy-Algorithms/Is_Subsequence.cpp

@@ -0,0 +1,34 @@
+/* Problem Statement
+Given a string s and a string t, check if s is subsequence of t.
+A subsequence of a string is a new string which is formed from the original string by deleting some(can be none) of the characters without disturbing the relative positions of the remaining characters. 
+(ie, "ace" is a subsequence of "abcde" while "aec" is not).
+*/
+#include<bits/stdc++.h>
+using namespace std;
+bool isSubsequence(string s, string t) {
+ int i, j = 0;
+ if (s.length() == 0) // empty string is always a subsequence
+ return true;
+ char c = s[0]; //c stores first character of s
+ if (t.length() < s.length()) // a string s containing less characters than t cannot be its subsequence
+ return false;
+ for (i = 0; i < t.length(); i++)
+ {
+ if (t[i] == c)
+ {
+ j++; //it moves the iterator to the next character of s
+ if (j == s.length()) //if the iterator has reached the limit of s , it means it is present as subsequence
+ return true;
+ c = s[j];
+ }
+ }
+ return false; //if the conditions are not satisified above, then s is not a subsequence of t
+}
+int main()
+{
+ string s, t;
+ cin >> s >> t;
+ cout << boolalpha; //to display true for 1 and false for 0
+ cout << isSubsequence(s, t);
+ return 0;
+}