Multiple Pointers - isSubsequence ::: Write a function called isSubsequence which takes in two strings and checks whether the characters in the first string form a subsequence of the characters in the second string. In other words, the function should check whether the characters in the first string appear somewhere in the second string, without their order changing.

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1 year ago by Yogesh Dv

Multiple Pointers - isSubsequence

Following is sample javascript code.

// Multiple Pointers - isSubsequence

// Examples:

// isSubsequence('hello', 'hello world'); // true
// isSubsequence('sing', 'sting'); // true
// isSubsequence('abc', 'abracadabra'); // true
// isSubsequence('abc', 'acb'); // false (order matters)
// Your solution MUST have AT LEAST the following complexities:

// Time Complexity - O(N + M)

// Space Complexity - O(1)

function isSubsequence(str1, str2){
  let left =0;
  let right =0;
   if (!str1) return true;
  while(right < str2.length){
    if(str1[left] === str2[right]) left ++;
    if(left === str1.length) return true;
    right ++;
  }
  return false;
}

console.log(isSubsequence('sing', 'sting'))