Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

Python: #!/usr/bin/env python
from __future__ import division, print_function
from sys import stdin


def main():
    n = int(stdin.readline())

    for _ in range(n):
        x = stdin.readline().rstrip()
        y = stdin.readline().rstrip()

        m = len(x)
        n = len(y)
        #assert 1 <= m <= 1000
        #assert 1 <= n <= 1000

        c = [[0]*(n+1) for _ in range(m+1)]

        for i in range(1, m+1):
            for j in range(1, n+1):
                if x[i-1] == y[j-1]:
                    c[i][j] = c[i-1][j-1] + 1
                elif c[i-1][j] >= c[i][j-1]:
                    c[i][j] = c[i-1][j]
                else:
                    c[i][j] = c[i][j-1]

        print(c[-1][-1])


main()

Python: def get_longest_count(X, Y):
  count = 0
  while len(X) > 0 and len(Y) > 0:
    if X[-1] != Y[-1]:
      return count + max(get_longest_count(X[:-1], Y), get_longest_count(X, Y[:-1]))
    else:
      X = X[:-1]
      Y = Y[:-1]
      count += 1
  return count

for i in range(int(input())):
  X = input()
  Y = input()
  print(get_longest_count(X, Y))

Python: def len_LCS(X,Y):
    x_l = len(X)
    y_l = len(Y)
    lcs_row = [0 for _ in range(x_l+1)]
    for j in range(y_l):
        y_j = Y[j]
        lcs_row_p = lcs_row[:]
        # lcs_row_p: [i] [i+1]
        # lcs_row  : [i] [i+1]
        for i in range(x_l):
            if X[i] == y_j:
                lcs_row[i+1] = lcs_row_p[i] + 1
            elif lcs_row[i] > lcs_row_p[i+1]:
                lcs_row[i+1] = lcs_row[i]
    return lcs_row[-1]
        
if __name__=='__main__':
    n = int(input())
    for _ in range(n):
        X = input()
        Y = input()
        print(len_LCS(X,Y))

Python: DP_MAX = 1000
dp = [0] * (DP_MAX + 1)

for i in range(DP_MAX + 1):
  dp[i] = [0] * (DP_MAX + 1)

def lcs(s, t):
  slen = len(s)
  tlen = len(t)

  for i in range(1, slen + 1):
    dp_i   = dp[i]
    dp_i_1 = dp[i-1]
    for j in range(1, tlen + 1):
      if s[i-1] == t[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[slen][tlen]

n = int(raw_input())

for i in range(n):
  x = raw_input()
  y = raw_input()
  print(lcs(x, y))

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C

????????±?????¨??????
"""
# 4/5??§Time Limit Exceeded 5.94s ????????????5s??\???????????????????????????



def prep_array(X, Y):
    """ ??????0???2?¬???????????????¨??????????????????????????\????????????????????§??????????????????????¨?(1000+1) """
    c = [[0]*1001 for _ in range(1000+1)]
    return c


def check_max(array):
    """ 2?¬????????????????????????§??????????????? """
    max_lcs = 0
    for row in array:
        temp_max = max(row)
        if temp_max > max_lcs:
            max_lcs = temp_max
    return max_lcs


def calc_lcs4(X, Y, c):
    """
    X[i]???for j?????????????????????????????°????????????????????§???
    4/5 ?????????????????????????????¨????????????????????????????????°??§6.9?§?
    """
    X = ' ' + X
    Y = ' ' + Y
    m = len(X)
    n = len(Y)

    pre_row = c[0]
    for i in range(1, m):
        row = c[i]
        XX = X[i]
        for j, YY in enumerate(Y):
            if XX == YY:
                row[j] = pre_row[j - 1] + 1
            elif pre_row[j] >= row[j - 1]:
                row[j]= pre_row[j]
            else:
                row[j] = row[j - 1]
        pre_row = row
    return check_max(c)



def calc_lcs3(X, Y, c):
    """
    X[i]???for j?????????????????????????????°????????????????????§???
    4/5 ?????????????????????????????¨????????????????????????????????°??§7.1?§?
    """
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y

    pre_row = c[0]
    for i in range(1, m+1):
        row = c[i]
        XX = X[i]
        for j in range(1, n+1):
            if XX == Y[j]:
                row[j] = pre_row[j - 1] + 1
            elif pre_row[j] >= row[j - 1]:
                row[j] = pre_row[j]
            else:
                row[j] = row[j - 1]
        pre_row = row
    return check_max(c)



def calc_lcs2(X, Y, c):
    """
    c[i][j]????????¢????????????????????????????????§?????????????????¨?????????????????°??????????????????????????£??????????????§???
    4/5 ?????????????????????????????¨????????????????????????????????°??§8.2?§?
    """
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y

    pre_row = c[0]
    for i in range(1, m+1):
        row = c[i]
        for j in range(1, n+1):
            if X[i] == Y[j]:
                row[j] = pre_row[j - 1] + 1
            elif pre_row[j] >= row[j - 1]:
                row[j] = pre_row[j]
            else:
                row[j] = row[j - 1]
        pre_row = row
    return check_max(c)



def calc_lcs(X, Y, c):
    """
    ??????????????¢?????´????????????????????????????£?????????????
    4/5 ?????????????????????????????¨????????????????????????????????°??§12.5?§?
    """
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y

    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
            elif c[i - 1][j] >= c[i][j - 1]:
                c[i][j] = c[i - 1][j]
            else:
                c[i][j] = c[i][j - 1]
    return check_max(c)


if __name__ == '__main__':
    # ??????????????\???
    num = int(input())
    # f = open('input.txt')
    # num = int(f.readline())

    for _ in range(num):
        X = input()
        Y = input()
        # X = f.readline().strip()
        # Y = f.readline().strip()

        # ???????????????
        result = calc_lcs4(X, Y, prep_array(X, Y))

        # ???????????¨???
        print(result)