Add solution for is subsequence

Author: kwnna15

two-pointer/is-subsequence/README.md

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+# 443. String Compression
+
+## Description
+See https://leetcode.com/problems/string-compression/description/
+
+## Problem
+Given an array of characters `chars`, compress it using the following algorithm:
+
+Begin with an empty string `s`. For each group of consecutive repeating characters in `chars`:
+
+If the group's length is `1`, append the character to `s`.
+Otherwise, append the character followed by the group's length.
+The compressed string `s` should not be returned separately, but instead, be stored in the input character array `chars`. Note that group lengths that are `10` or longer will be split into multiple characters in chars.
+
+After you are done modifying the input array, return the new length of the array.
+
+You must write an algorithm that uses only constant extra space.
+
+## Example 1
+
+```
+Input: chars = ["a","a","b","b","c","c","c"]
+Output: Return 6, and the first 6 characters of the input array should be: ["a","2","b","2","c","3"]
+Explanation: The groups are "aa", "bb", and "ccc". This compresses to "a2b2c3".
+```
+
+## Example 2
+
+```
+Input: chars = ["a"]
+Output: Return 1, and the first character of the input array should be: ["a"]
+Explanation: The only group is "a", which remains uncompressed since it's a single character.
+```
+
+## Example 3
+
+```
+Input: chars = ["a","b","b","b","b","b","b","b","b","b","b","b","b"]
+Output: Return 4, and the first 4 characters of the input array should be: ["a","b","1","2"].
+Explanation: The groups are "a" and "bbbbbbbbbbbb". This compresses to "ab12".
+```
+
+## Constraints
+
+```
+1 <= chars.length <= 2000
+chars[i] is a lowercase English letter, uppercase English letter, digit, or symbol.
+```

two-pointer/is-subsequence/subsequence.py

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+def is_subsequence(s: str, t: str) -> bool:
+    i, j = 0, 0
+    while i < len(s) and j < len(t):
+        if s[i] == t[j]:
+            i += 1
+        j += 1
+    return i == len(s)

two-pointer/is-subsequence/subsequence_test.py

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+from subsequence import is_subsequence
+
+def test_example_1():
+    s = "abc"
+    t = "ahbgdc"
+    assert is_subsequence(s, t) == True
+
+def test_example_2():
+    s = "axc"
+    t = "ahbgdc"
+    assert is_subsequence(s, t) == False
+
+def test_example_3():
+    s = ""
+    t = "ahbgdc"
+    assert is_subsequence(s, t) == True
+
+def test_example_4():
+    s = "abc"
+    t = ""
+    assert is_subsequence(s, t) == False
+
+def test_example_5():
+    s = "ace"
+    t = "abcde"
+    assert is_subsequence(s, t) == True