Go: package main

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

func max(x, y int) int {
	if x < y {
		return y
	} else {
		return x
	}
}

/*********************************************************************
長さmの列X_(m)と長さnの列Y_(n)の最長共通部分列LCSは、
	(1)X[m] == Y[n]ならば、X_(m-1)とY_(n-1)のLCSにX[m]を繋げたもの
	(2)X[m] != Y[n]ならば、X_(m-1)とY_(n)のLCSもしくはX_(m)とY_(n-1)のLCS
	のいずれかのうち長い方

c[m+1][n+1]：c[i][j]にX_(i)とY_(j)のLCSの長さを格納する二次元配列
*********************************************************************/

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		s1 := scanner.Text()
		scanner.Scan()
		s2 := scanner.Text()
		s1, s2 = s1 + " ", s2 + " "
		c := make([][]int, len(s1))
		for i := range c {
			c[i] = make([]int, len(s2))
		}

		LCS := 0

		for i := 1; i < len(s1); i++ {
			for j := 1; j < len(s2); j++ {
				if s1[i] == s2[j] {
					c[i][j] = c[i-1][j-1] + 1
				} else {
					c[i][j] = max(c[i-1][j], c[i][j-1])
				}
				LCS = max(LCS, c[i][j])
			}
		}
		fmt.Println(LCS)
	}
}

Python: import bisect


def LCS(S, T):
    N = len(S)
    M = len(T)
    dp = [[0] * (M + 1) for _ in range(N + 1)]

    for i, s in enumerate(S, start=1):
        for j, t in enumerate(T, start=1):
            if s == t:
                dp[i][j] = dp[i - 1][j - 1] + 1
            else:
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
    return dp[N][M]


def LCS_HTKB(S, T):
    T = T[::-1]
    memo = []

    for s in S:
        i = T.find(s) + 1
        while i:
            j = bisect.bisect_left(memo, -i)
            if j >= len(memo):
                memo.append(-i)
            else:
                memo[j] = -i
            i = T.find(s, i) + 1
    return len(memo)


if __name__ == "__main__":
    Q = int(input())
    ans = []
    for _ in range(Q):
        ans.append(LCS_HTKB(input(), input()))
    print(*ans, sep="\n")

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

def lcs_improved(X, Y):
    hist = [0] # yの文字cまでを見た時に, hist[i]以降の文字列において, 共通文字のうち, 一番小さいindexのもの
    for c in Y:
        for i in range(len(hist)-1, -1, -1):
            next_match_i = X.find(c, hist[i])+1
            if next_match_i:
                if i+1 < len(hist):
                    hist[i+1] = min(hist[i+1], next_match_i)
                else:
                    hist.append(next_match_i)
    return len(hist)-1

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

Python: #!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
input:
3
abcbdab
bdcaba
abc
abc
abc
bc

output:
4
3
2

"""
import sys


def lcs(w1, w2):
    m, n = len(w1), len(w2)
    dp = [[0] * (n + 1) for _ in range(m + 1)]
    max_l = 0
    for i in range(1, m + 1):
        for j in range(1, n + 1):
            if w1[i - 1] == w2[j - 1]:
                dp[i][j] = dp[i - 1][j - 1] + 1
            else:
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
            max_l = max(max_l, dp[i][j])

    return max_l


def solve():
    input_ = sys.stdin.readlines()
    pair_num = int(input_[0])

    word_list = input_[1:]
    # assert len(word_list) == 2 * pair_num

    for pair in zip(word_list[::2], word_list[1::2]):
        cw1, cw2 = map(lambda x: x.strip(), pair)
        print(lcs(cw1, cw2))
        # l1, l2 = len(cw1), len(cw2)
        # print(lcs_recursive(cw1, cw2, l1, l2))

    return


if __name__ == '__main__':
    solve()

Python: def lcs(s1, s2):
    n, m = len(s1), len(s2)
    dp = [[0] * (m+1) for _ in range(n+1)]

    for i in range(1, n+1):
        for j in range(1, m+1):
            if s1[i-1] == s2[j-1]:
                dp[i][j] = dp[i-1][j-1] + 1
            else:
                dp[i][j] = max(dp[i-1][j], dp[i][j-1])

    return dp[n][m]

def solve():
    N = int(input())
    for _ in range(N):
        a = input()
        b = input()
        print(lcs(a, b))

if __name__ == '__main__':
    solve()

Python: def lcs_len(x, y):
    ly = len(y)
    tcsl = [0 for i in range(ly + 1)]
    for x_i in x:
        pre_tcsl = list(tcsl)
        for j in range(ly):
            if x_i == y[j]:
                tcsl[j] = pre_tcsl[j - 1] + 1
            else:
                tcsl[j] = max(pre_tcsl[j], tcsl[j - 1])
    print(tcsl[j])


q = int(input())

for i in range(q):
    ax = input()
    ay = input()
    lcs_len(ax, ay)

Python: for _ in[0]*int(input()):
 X,z=input(),[]
 for y in input():
  s=i=0
  for k in z:
   t=X.find(y,s)+1
   if t<1:break
   if t<k:z[i]=t
   s=k;i+=1
  else:
   t=X.find(y,s)+1
   if t:z+=[t]
 print(len(z))

Python: import sys

def LCS():
    str1=input()
    str2=input()

    l=len(str1)
    m=len(str2)
    x1=[0 for i in range(m+1)]
    for i in range(l):
        e1=str1[i]
        x2=x1+[]
        for j in range(m):
            if e1 == str2[j]:
                x1[j+1] = x2[j] + 1
            elif x1[j+1]<x1[j]:
                x1[j+1] = x1[j]
    return x1[-1]

n = int(input())
for i in range(n):
    
    print(LCS())

Python: import sys
e=sys.stdin.readline
for _ in[0]*int(e()):
 X,z=e(),[]
 for y in e():
  s=i=0
  for k in z:
   t=X.find(y,s)+1
   if t<1:break
   if t<k:z[i]=t
   s=k;i+=1
  else:
   t=X.find(y,s)+1
   if t:z+=[t]
 print(len(z)-1)

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 = [[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
            elif count_list[i - 1][j] >= count_list[i][j - 1]:
                count_list[i][j] = count_list[i - 1][j]
            else:
                count_list[i][j] = count_list[i][j - 1]

    return count_list[m][n]


def lcs_better(A, B):
    costs = [0]
    for c in B:
        for index in range(len(costs) - 1, -1, -1):
            print(costs, index + 1)
            x_findex_index = A.find(c, costs[index])
            if x_findex_index != -1:
                if index + 1 < len(costs):
                    costs[index + 1] = min(costs[index + 1], x_findex_index + 1)
                else:
                    costs.append(x_findex_index + 1)
    return len(costs) - 1


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_better(word_list[k].strip(), word_list[k + 1].strip()))

Python: e=input
a=[]
for _ in[0]*int(e()):
 X,z=e(),[]
 for y in e():
  s=i=0
  for k in z:
   t=X.find(y,s)+1
   if t<1:break
   if t<k:z[i]=t
   s=k;i+=1
  else:
   t=X.find(y,s)+1
   if t:z+=[t]
 a+=[len(z)]
print('\n'.join(map(str,a)))

Python: from sys import stdin

X = [ 0 for i in range(1000) ]
Y = [ 0 for i in range(1000) ]
Z = [[0 for i in range(100)]for i in range(100)]

def getLCS(l) :
	xlen = len(X[l])
	ylen = len(Y[l])

	for i in range(1,xlen+1) :
		for j in range(1,ylen+1) :
			a = 1 if X[l][i-1] == Y[l][j-1] else 0
			Z[i][j] = max(Z[i-1][j-1] + a, Z[i-1][j], Z[i][j-1])

	return Z[xlen][ylen]

n = int(input())
for l in range(n) :
	X[l] = stdin.readline().strip()
	Y[l] = stdin.readline().strip()
	print(getLCS(l))