Go: package main

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

type Position struct {
	X int
	Y int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}
	for i := 0; i < n; i++ {
		strX := nextText(sc)
		strY := nextText(sc)
		fmt.Println(calcLcs(strX, strY))
	}
}

func calcLcs(strX, strY string) int {
	return lcs(strX, strY, Position{0, 0}, make(map[Position]int))
}

func lcs(strX string, strY string, position Position, memo map[Position]int) int {
	if position.X >= len(strX) || position.Y >= len(strY) {
		return 0
	}
	if v, ok := memo[position]; ok {
		return v
	}
	if strX[position.X] == strY[position.Y] {
		result := lcs(strX, strY, Position{position.X + 1, position.Y + 1}, memo)
		memo[position] = result + 1
		return memo[position]
	} else {
		result1 := lcs(strX, strY, Position{position.X + 1, position.Y}, memo)
		result2 := lcs(strX, strY, Position{position.X, position.Y + 1}, memo)
		var result int
		if result1 > result2 {
			result = result1
		} else {
			result = result2
		}
		memo[position] = result
		return result
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

Python: q = int(input())

l = []
x = ""
y = ""
"""
def lcs(yIndex, xIndex):
    global l, x, y
    if xIndex == 0 and yIndex == 0:
        return 0
    elif xIndex == 0:
        return l[yIndex - 1][0]
    elif yIndex == 0:
        return l[0][xIndex - 1]
    elif x[xIndex] == y[yIndex]:
        return 1 + l[yIndex - 1][xIndex - 1]
    else:
        if l[yIndex][xIndex - 1] > l[yIndex - 1][xIndex]:
            return l[yIndex][xIndex - 1]
        else:
            return l[yIndex - 1][xIndex]
        #return max(l[yIndex][xIndex - 1], l[yIndex - 1][xIndex])
 """
for i in range(q):
    x = input()
    y = input()
 
    yLen = len(y)
    xLen = len(x)
    l = [[-1] * xLen for j in range(yLen)]

    for j in range(yLen):
        for k in range(xLen):
            if k == 0 and j == 0:
                l[j][k] = 0
            elif k == 0:
                l[j][k] = l[j - 1][0]
            elif j == 0:
                l[j][k] =  l[0][k - 1]
            elif x[k] == y[j]:
                l[j][k] =  1 + l[j - 1][k - 1]
            else:
                if l[j][k - 1] > l[j - 1][k]:
                    l[j][k] = l[j][k - 1]
                else:
                    l[j][k] = l[j - 1][k]
            #l[j][k] = lcs(j, k)
 
    print(l[yLen- 1][xLen - 1])

Python: def main():
    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])
if __name__ == "__main__":
    main()

Python: # -*- coding: utf-8 -*-

import random
import sys
import os
import pprint


def LCS(s0, s1):
    # print(s0)
    # print(s1)
    m = len(s0)
    n = len(s1)

    # memo[i][j]
    memo = [[0] * n for i in range(m)]
    # pprint.pprint(memo)

    # fill at index 0
    index = s0.find(s1[0])
    if index != -1:
        for i in range(index, m):
            memo[i][0] = 1

    index = s1.find(s0[0])
    if index != -1:
        for j in range(index, n):
            memo[0][j] = 1

    """
    for i in range(m):
        if s1[0] in s0[0:i+1]:
            memo[i][0] = 1
    for j in range(n):
        if s0[0] in s1[0:j+1]:
            memo[0][j] = 1
    """

    # fill memo
    for i in range(1, m):
        for j in range(1, n):
            # same last
            if s0[i] == s1[j]:
                memo[i][j] = memo[i-1][j-1] + 1
            else:
                memo[i][j] = max(memo[i-1][j], memo[i][j-1])
    return memo[m-1][n-1]


"""
def LCS_better(s0, s1):
    dp = [0] * len(s1) # cost use till j
    for c in s0:
        tmp = dp[:]
        for j in range(len(s1)):
            if c == s1[j]:
                dp[j + 1] = tmp[j] + 1
            elif dp[j + 1] < dp[j]:
                dp[j + 1] = dp[j]
    return dp[-1]
"""

#fd = os.open('ALDS1_10_C.txt', os.O_RDONLY)
#os.dup2(fd, sys.stdin.fileno())

n = int(input())
for _ in range(n):
    s0 = input()
    s1 = input()
    l = LCS(s0, s1)
    #l2 = LCS_better(s0, s1)
    print(l)

Python: def lcs(x, y):
    L = []
    for y_k in y:
        si = 0
        for i, cri in enumerate(L):
            chi = x.find(y_k, si) + 1
            if not chi:
                break
            L[i] = min(cri, chi)
            si = cri
        else:
            chi = x.find(y_k, si) + 1
            if chi:
                L.append(chi)
    return len(L)


if __name__ == "__main__":
    N = int(input())
    ans = []
    for _ in range(N):
        X = input()
        Y = input()
        print(lcs(X, Y))

Python: from sys import stdin
input = stdin.readline

N = 1000

def lcs(X, Y):
    c = [[0]*(N+1) for _ in range(N+1)]
    maxl = 0
    X = ' ' + X # 1オリジンにする
    Y = ' ' + Y
    pre_row = c[0]
    for i, x in enumerate(X):
        if i == 0:
            continue
        row = c[i]
        for j, y in enumerate(Y):
            if j == 0:
                continue
            if x == y:
                value = pre_row[j-1] + 1
                row[j] = value
                if maxl < value: # maxlの更新はこの時しか起こらない
                    maxl = value
            else:
                pre_row_j = pre_row[j]
                row_j_1 = row[j-1]
                value = row_j_1
                if pre_row_j > row_j_1:
                    value = pre_row_j # max関数だと、とても遅い
                row[j] = value
        pre_row = row # 今の列が次の列にとって一つ前の列になる

    return maxl

n = int(input())
for _ in range(n):
    s1 = input()[:-1]
    s2 = input()[:-1]
    print(lcs(s1, s2))

Python: import sys

def lcm(c,i, j):
    if c[i][j]>0: return c[i][j]        
    if i==0 or j==0:
        return 0
    elif x[i]==y[j]:
        c[i][j] = lcm(c,i-1,j-1)+1
        return c[i][j]
    else:
        c[i][j] = max(lcm(c,i,j-1), lcm(c,i-1,j))
        return c[i][j]

for _ in range(int(sys.stdin.readline())):
    x = sys.stdin.readline()
    y = sys.stdin.readline()
    c = [[0 for _ in range(len(x)+2)] for _ in range(len(y)+2)] 
    print(lcm(c,len(x)-1,len(y)-1))

Python: q = int(input())
ans = []
for _ in range(q):
    x = input()
    y = input()
    m = len(x)
    n = len(y)
    c = [0] * (n + 1)
    for i in range(m):
        tmp = x[i]
        c_ = c[:]
        for j in range(n):
            if tmp == y[j]:
                c[j + 1] = c_[j] + 1
            elif c[j + 1] < c[j]:
                c[j + 1] = c[j]
    ans.append(c[-1])

print(*ans, sep="\n")