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3

# Longest Common Subsequence

Difficulty: MEDIUM
Contributed By
Priyaraj |Level 1

Problem Statement

#### A String ‘a’ is a subsequence of a String ‘b’ if ‘a’ can be obtained from ‘b’ by deletion of several (possibly, zero or all) characters. A common subsequence of two Strings is a subsequence that is common to both Strings.

##### Input Format :
``````The first line contains an integer ‘T’ denoting the number of test cases. Then each test case follows.

The first input line of each test case contains two space-separated Strings “STR1” and “STR2” representing two Strings.
``````
##### Output Format :
``````For each test case, print the length of the longest common subsequence.

Print the output of each test case in a separate line.
``````
##### Note:
``````You are not required to print the expected output; it has already been taken care of. Just implement the function.
``````
##### Constraints :
``````1 <= T <= 50
1 <= |STR1| <= 10^2
1 <= |STR2| <= 10^2

Where |STR1| and |STR2| denote the length of “STR1” and “STR2” respectively.

Time Limit: 1 sec
``````
##### Sample Input 1 :
``````2
pqr tpuqvr
``````
##### Sample output 1 :
``````2
3
``````
##### Explanation For Sample Input 1 :
``````For the first test case, the longest common subsequence is “ab” and its length is 2.

For the second test case, the longest common subsequence is “pqr” and its length is 3.
``````
##### Sample Input 2 :
``````2
a b
a a
``````
##### Sample output 2 :
``````0
1
``````
##### Explanation For Sample Input 2 :
``````For the first test case, any non-empty common subsequence doesn’t exist.

For the second test case, the longest common subsequence is “a” and its length is 1.
``````
Console