Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
			}
		}
	}
	return dp[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
input:
3
abcbdab
bdcaba
abc
abc
abc
bc

output:
4
3
2

"""
import sys


def lcs(A, B):
    m, n = len(A), len(B)
    count_list = tuple([[0] * (n + 1) for _ in range(m + 1)])

    for i in range(1, m + 1):
        for j in range(1, n + 1):
            if A[i - 1] == B[j - 1]:
                count_list[i][j] = count_list[i - 1][j - 1] + 1
            else:
                count_list[i][j] = max(count_list[i - 1][j], count_list[i][j - 1])

    return count_list[m][n]


def lcs_recursive(A, B, m, n):
    if m == 0 or n == 0:
        return 0
    elif A[m - 1] == B[n - 1]:
        return 1 + lcs_recursive(A, B, m - 1, n - 1)
    else:
        return max(lcs_recursive(A, B, m, n - 1), lcs_recursive(A, B, m - 1, n))


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    pair_num = int(_input[0])

    word_list = _input[1:]
    # assert len(word_list) == 2 * pair_num
    # for k in range(0, len(word_list), 2):
    #     print(lcs(word_list[k].strip(), word_list[k + 1].strip()))

    for pair in zip(word_list[::2], word_list[1::2]):
        w1, w2 = map(lambda x: x.strip(), pair)
        l1, l2 = len(w1), len(w2)
        print(lcs_recursive(w1, w2, l1, l2))

Python: def L_common(str1,str2):
    d = [0 for i in range(len(str2)+1)]
    
    for n1 in str1:
        tmp = d[:]
        for (j,n2) in enumerate(str2):
            if n1 == n2:
                d[j+1] = tmp[j]+1
            elif d[j+1]<d[j]:
                d[j+1] = d[j]
    return d[len(str2)]

n = int(input())
stock = []
for i in range(n):
    x = input()
    y = input()
    stock.append(L_common(x,y))

for i in stock:
    print(i)

Python: n=int(input())

for i in range(n):
    a=list(input())
    b=list(input())

    r=[[0 for j in range(len(b)+1)]for i in range(len(a)+1)]

    for j in range(1,len(a)+1):
        for k in range(1,len(b)+1):
            c=max(r[j-1][k-1],r[j-1][k],r[j][k-1])
            if a[j-1]==b[k-1]:
                c=max(r[j-1][k-1]+1,r[j-1][k],r[j][k-1])
            
            r[j][k]=c
  
    
    print(r[len(a)][len(b)])

Python: def lcs(s1, s2):
    dp = []
    for s2_k in s2:
        bgn_idx = 0
        for i, cur_idx in enumerate(dp):
            chr_idx = s1.find(s2_k, bgn_idx) + 1
            if not chr_idx:
                break
            dp[i] = min(cur_idx, chr_idx)
            bgn_idx = cur_idx
        else:
            chr_idx = s1.find(s2_k, bgn_idx) + 1
            if chr_idx:
                dp.append(chr_idx)
    return len(dp)

n = int(input())
for _ in range(n):
    x = input()
    y = input()
    print(lcs(x, y))

Python: def solve_L():
    X = input()
    Y = input()
  
    a = len(X)
    b = len(Y)
    c1 = [0 for i in range(b+1)]
    for i in range(a):
        e1 = X[i]
        c2 = c1+[]
        for j in range(b):
            if e1 == Y[j]:
                c1[j+1] = c2[j] + 1
            elif c1[j+1] < c1[j]:
                c1[j+1] = c1[j]
    return c1[-1]
  
n = int(input())
ans = [[] for i in range(n)]
for i in range(n):
    ans[i] = solve_L()
for i in range(n):
  print(ans[i])

Python: def Ics(X, Y):
    m = len(X)
    n = len(Y)
    maxl = 0
    for i in range(m + 1):
        c[i][0] = 0
    for j in range(1, n + 1):
        c[0][j] = 0
    for i in range(1, m + 1):
        for j in range(1, n + 1):
            if(X[i] == Y[j]):
                c[i][j] = c[i - 1][j - 1] + 1
            else:
                c[i][j] = max(c[i][j - 1], c[i - 1][j])
            maxl = max(maxl, c[i][j])
    return maxl

q = int(input())
t = []
for i in range(n):
    s1 = input().rstrip()
    s2 = input().rstrip()
    t.append(lcs(s1, s2))
print(*t, sep="\n")

Python: def common(x,y):
    n = len(x)
    m = len(y)
    c1 = [0for i in range(m+1)]
    for i in range(n):
        e1 = x[i]
        c2 = c1[:]
        for j in range(m):
            if (e1 == y[j]):
                c1[j+1] = c2[j] + 1
            elif (c1[j+1] < c1[j]):
                c1[j+1] = c1[j]
    return(c1[-1])


t = int(input())
for w in range(t):
    fseq = str(input()) ##Xk
    sseq = str(input()) ##Yl
    print(common(fseq,sseq))

Python: # -*- coding:utf-8 -*-
import sys
 
 
def search(x, y):
    x_length = len(x)
    y_length = len(y)
    memo = [[0] * (y_length + 1) for i in range(x_length + 1)]
    for i, ch_x in enumerate(x, 1):
        row = memo[i]
        pre_row = memo[i-1]
        for j, ch_y in enumerate(y, 1):
            if ch_x == ch_y:
                row[j] = pre_row[j-1] + 1
            elif pre_row[j] < row[j-1]:
                row[j] = row[j-1]
            else:
                row[j] = pre_row[j]
    return memo[-1][-1]
 
 
if __name__ == "__main__":
    n = int(input())
    strs = [list(val) for val in sys.stdin.read().splitlines()]
    result = [search(strs[i*2], strs[i*2+1]) for i in range(n)]
    print(*result, sep="\n")

Python: q=int(input())

def lastindex(a,x):
    try:
        return len(a)-a[::-1].index(x)-2
    except:
        return(-1)
for repeat in range(q):
    X=input()
    Y=input()
    lenX=len(X)
    lenY=len(Y)
    Z=[[0 for i in range(lenY)] for i in range(lenX)]

    if X[0]==Y[0]:
        Z[0][0]=1
    
    for i in range(1,lenY):
        if Z[0][i-1]==1:
            Z[0][i]=1
        else:
            if Y[i]==X[0]:
                Z[0][i]=1

    for j in range(lenX):
        if Z[j-1][0]==1:
            Z[j][0]=1
        else:
            if X[j]==Y[0]:
                Z[j][0]=1


    for i in range(1,lenX):
        for j in range(1,lenY):
            x=lastindex(X[:i+1:],Y[j])
            y=lastindex(Y[:j+1:],X[i])

            if x!=-1 and y!=-1:
                Z[i][j]=max(Z[x][j-1],Z[i-1][y])+1
            elif x!=-1:
                Z[i][j]=Z[x][j-1]+1
            elif y!=-1:
                Z[i][j]=Z[i-1][y]+1

            Z[i][j]=max(Z[i][j],Z[i-1][j],Z[i][j-1])

    print(Z[-1][-1])

Python: from pprint import pprint
def main():
    fp=open("result.txt","w")
    n = int(input())
    for i in range(n):
        a = input()
        b = input()
        na=len(a)
        nb=len(b)
        array = [[0]*nb for i in range(na)]
        #array = [[0 for i in range(nb)] for j in range(na)]
        for i in range(na):
            for j in range(nb):
                c = 0
                if i==0:
                    if a[i]==b[j]:
                        array[i][j]=1
                elif j==0:
                    if a[i]==b[j]:
                        array[i][j]=1
                else:
                    if a[i] == b[j]:
                        c = 1
                        array[i][j] = max(
                            array[i-1][j],
                            array[i][j-1],
                            array[i-1][j-1]+c)
        print(array[na-1][nb-1])
    fp.close()
if __name__ == "__main__":
    main()