Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

Python: def lcs(X, Y):
    C = []
    for y in Y:
        bgn_idx = 0
        for i, cur_idx in enumerate(C):
            chr_idx = X.find(y, bgn_idx) + 1
            if chr_idx == 0:
                break
            C[i] = min(cur_idx, chr_idx)
            bgn_idx = cur_idx
        chr_idx = X.find(y, bgn_idx) + 1
        if chr_idx != 0:
            C.append(chr_idx)
    return len(C)

q = int(input())
for _ in range(q):
    X = input()
    Y = input()
    print(lcs(X, Y))

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: ascii_letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

def llcs(x, y):
    pm = dict((zip(ascii_letters, [0] * 52)))
    for c in pm:
        for i, xc in enumerate(x):
            if c == xc:
                pm[c] |= (1 << i)
    
    V = (1 << len(x)) - 1
    
    for yc in y:
        V = ((V + (V & pm[yc])) | (V & ~pm[yc]))
    
    ans = bin(V)[-len(x):].count('0')
    
    return ans

from sys import stdin

def solve():
    #file_input = stdin
    file_input = open("ALDS1_10_C_in_4", 'r')
    q = int(file_input.readline())
    for i in range(q):
        s1 = file_input.readline().rstrip()
        s2 = file_input.readline().rstrip()
        print(llcs(s1, s2))

solve()

Python: 
def LCS(x, y):
    dp = {}
    for i in range(len(x)+1):
        dp[i] = {0: 0}
    for j in range(len(y)+1):
        dp[0][j] = 0
    
    for i in range(1, len(x)+1):
        for j in range(1, len(y)+1):
            if x[i-1] == y[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[len(x)][len(y)]

q = int(raw_input())
for i in range(q):
    X = raw_input()
    Y = raw_input()
    print(LCS(X, Y))

Python: n=int(input())
x=[]
y=[]
for k in range(n):
	dp=[[0 for i in range(1000)] for j in range(1000)]
	x=list(input())
	y=list(input())
	for i in range(len(x)):
		for j in range(len(y)):
			
			if i is 0:
				if x[i] is y[j]:
					dp[i][j]=1
				else:
					dp[i][j]=dp[i][j-1]
			if j is 0:
				if x[i] is y[j]:
					dp[i][j]=1
				else:
					dp[i][j]=dp[i-1][j]

	for i in range(len(x)):
		tmp=0
		for j in range(len(y)):
			if i is not 0 and j is not 0:
				if x[i] is y[j] and tmp is 0:
					dp[i][j]=max(dp[i][j-1],dp[i-1][j])+1
					tmp+=1
				else:
					dp[i][j]=max(dp[i][j-1],dp[i-1][j])

	print(dp[len(x)-1][len(y)-1])
#	print(x,y)
#	for i in range(7):
#		print(dp[i])

Python: 
def main():
    n = int(input())
    for i in range(n):
        a = input()
        b = input()
        na=len(a)
        nb=len(b)
        array = [[0 for i in range(nb)] for j in range(na)]
        for i in range(na):
            for j in range(nb):
                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:
                    c = 0
                    if a[i] == b[j]:
                        c = 1
                    array[i][j] = array[i-1][j-1]+c 
                    """
                    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: #!/usr/bin/python3
import itertools
# main
q = int(input())
for a in range(q):
    X = input()
    Y = input()
    cost = [0]
    for c in Y:
        for i in range(len(cost) - 1, -1, -1):
            index = X.find(c, cost[i]) + 1
            if index:
                if i + 1 < len(cost):
                    cost[i + 1] = min(cost[i + 1], index)
                else:
                    cost.append(index)
    print(len(cost) - 1)

Python: n = int(input())

for k in range(n):
    a = input()
    b = input()
    len_a, len_b = len(a), len(b)
    table = [[0] * (len_b +1) for i in range(len_a + 1)]
    
    for i in range(len_a):
        a_i = a[i]
        table_i = table[i]
        for j in range(len_b):
            if a_i == b[j]:
                table[i+1][j+1] = table_i[j] + 1
            else:
                table[i+1][j+1] = max(table_i[j+1],table[i+1][j])
    print(table[len_a][len_b])

Python: def num_substr(s, t):
    dp = {}
    for i in range(len(s) + 1):
        dp[i] = {0: 0}
    for j in range(len(t) + 1):
        dp[0][j] = 0
     
    for i in range(1,len(s)+1):
        si_1 = s[i-1]
        dpi = dp[i]
        dpi_1 = dp[i-1]
        Flag=False
        for j in range(1,len(t)+1):
            d=1 if s[i-1] == t[j-1] and dpi_1[j-1] == dp[i][j-1] else 0
            dpi[j] = max(dpi_1[j] ,
                           dpi[j-1] +d)
    return dp[len(s)][len(t)]
 
n = int(input())
for i in range(n):
    s = input()
    t = input()
    print(num_substr(s,t))

Python: def lcs(X, Y):
	m = len(X)
	n = len(Y)
	c = [0 for i in range(n+1)]
	for i in range(m):
		pre_c = c[:]
		XX = X[i]
		for j in range(n):
			if XX == Y[j]:
				c[j+1] = pre_c[j] + 1
			elif c[j + 1] < c[j]:
				c[j+1] = c[j]
	return c[-1]

if __name__ == "__main__":
	q = int(input())
	for _ in range(q):
		X = input()
		Y = input()
		print(lcs(X, Y))