Go: package main

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

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

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

????????±?????¨??????
"""
# 4/5??§Time Limit Exceeded 5.20s ????????????5s??\???????????????????????????

c = []
def prep_array(X, Y):
    global c
    """ ??????0???2?¬???????????????¨??????????????????????????\????????????????????§??????????????????????¨?(1000+1)??\???????????? """
    # from array import array
    # c = [array('I', [0] * (len(X)+1)) for _ in range(len(Y)+1)]  #  array??§??¨???
    c = [[0]*(len(Y)+2) for _ in range(len(X)+2)] #  ???????????§??¨???
    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):
    """
    Y[j]?????¢???????????????????????´
    ?????????????????????????????°?????????????????????????????´
    ????????±?????¨???????????¢??°?????§?¨????????????????????????´
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 5.6?§?
    """
    X = ' ' + X
    Y = ' ' + Y
    m = len(X)
    n = len(Y)
    max_lcs = 0

    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:
                pr_j1 = pre_row[j - 1]
                row[j] = pr_j1 + 1
                if pr_j1+1 > max_lcs:
                   max_lcs = pr_j1 + 1
            else:
                pr_j = pre_row[j]
                r_j1 = row[j-1]
                if pr_j >= r_j1:
                    row[j] = pr_j
                else:
                    row[j] = r_j1
        pre_row = row
    return max_lcs


def calc_lcs3(X, Y, c):
    """
    X[i]???for j?????????????????????????????°(XX)????????????????????§???
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 6.5?§?
    """
    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]????????¢????????????????????????????????§???????????????(row)??¨?????????(pre_row)????????°??????????????????????????£??????????????§???
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 7.5?§?
    """
    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_lcs1(X, Y):
    """
    ?????????????????????array?????????????????¨???byte???????????¨????????¨????§??????????????????????????????????????????§?????¨???????????£?????????int???????????¨???
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 18.5?§?
    """
    from array import array
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y
    c = array('i', [0] * (1024 * 1024))
    for i in range(1, m+1):
        for j in range(1, n+1):
            if X[i] == Y[j]:
                c[i*1024 + j] = c[(i-1)*1024 + j - 1] + 1
            elif c[(i-1)*1024 + j] >= c[i*1024 + j - 1]:
                c[i*1024 + j] = c[(i-1)*1024 + j]
            else:
                c[i*1024 + j] = c[i*1024 + j - 1]
    return max(c)


def calc_lcs1_1(X, Y):
    """
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 7.1?§?
    """
    from array import array
    X = ' ' + X
    Y = ' ' + Y
    m = len(X)
    n = len(Y)
    max_lcs = 0
    C = [array('I', [0] * n) for _ in range(m)]

    pre_row = C[0]
    for i in range(1, m):
        row = C[i]
        XX = X[i]
        for j, YY in enumerate(Y[1:]):
            if XX == YY:
                pr_j1 = pre_row[j-1]
                row[j] = pr_j1 + 1
                if row[j] > max_lcs:
                    max_lcs = pr_j1 + 1
            else:
                pr_j = pre_row[j]
                r_j1 = row[j-1]
                if pr_j >= r_j1:
                    row[j] = pr_j
                else:
                    row[j]= r_j1
        pre_row = row
    return max_lcs


def calc_lcs(X, Y, c):
    """
    ??????????????¢?????´????????????(??????)????????????????£?????????????
    4/5 ?????????????????????????????¨?????????????????????????????°????????¨??????????????? 11.3?§?
    ????????????????????¨????????????????????¢??°??§?¶?????????????????????§?????¢??°???????????????????????????????????????
    """
    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().strip()
        Y = input().strip()

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

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

Python: def lcs(x, y):
    m = len(x)
    n = len(y)
    c = [[0] * 1001 for i in range(1002)]
    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
            else:
                c[i][j] = max(c[i - 1][j], c[i][j - 1])
    return max([e for l1 in c for e in l1])

if __name__ == '__main__':
    n = int(input().rstrip())
    for i in range(n):
        s1 = input().rstrip()
        s2 = input().rstrip()
        print(lcs(s1, s2))

Python: import sys
sys.setrecursionlimit(10000)

def calc(x,y):
    i = len(x)
    j = len(y)
    if d[i][j]:
        return d[i][j]
    else:
        if i == 1:
            if x in y:
                d[i][j] = 1
                return 1
            else:
                d[i][j] = 0
                return 0
        elif j == 1:
            if y in x:
                d[i][j] = 1
                return 1
            else:
                d[i][j] = 0
                return 0
        else:
            if x[-1] == y[-1]:
                tmp = max(calc(x[:-1],y[:-1])+1,calc(x[:-1],y),calc(x,y[:-1]))
                d[i][j] = tmp
                return tmp
            else:
                tmp = max(calc(x[:-1],y),calc(x,y[:-1]))
                d[i][j] = tmp
                return tmp
        
q = int(input())
for i in range(q):
    x = input()
    y = input()
    d = [[None for _ in range(len(y)+1)] for _ in range(len(x)+1)]
    print(calc(x,y))