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: 
def main():
    n = int(input())
    for i in range(n):
        a = input()
        b = input()
        array = [[0 for i in range(len(b))] for j in range(len(a))]
        """
        for i in range(len(a)):
            if a[i]==b[0]:
                array[i][0]=1
        for j in range(len(b)):
            if b[j]==a[0]:
                array[0][j]=1 
        """
        for i in range(len(a)):
            for j in range(len(b)):
                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] = max(
                                        array[i-1][j],
                                        array[i][j-1],
                                        array[i-1][j-1]+c)
        print(array[len(a)-1][len(b)-1])
        #p.pprint(array)
if __name__ == "__main__":
    main()

Python: def lcs_len(x, y):
    ly = len(y)
    tcsl = [0] * (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: 
def LCS(x, y):
    len_x = len(x)
    len_y = len(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: q=int(input())

def lastindex(a,x):
    try:
        return len(a)-a[::-1].index(x)-2
    except:
        return(-1)
for repeat in range(q):
    X=input()
    Y=input()
    lenX=len(X)
    lenY=len(Y)
    Z=[[0 for i in range(lenY)] for i in range(lenX)]

    if X[0]==Y[0]:
        Z[0][0]=1
    
    for i in range(1,lenY):
        if Z[0][i-1]==1:
            Z[0][i]=1
        else:
            if Y[i]==X[0]:
                Z[0][i]=1

    for j in range(lenX):
        if Z[j-1][0]==1:
            Z[j][0]=1
        else:
            if X[j]==Y[0]:
                Z[j][0]=1


    for i in range(1,lenX):
        for j in range(1,lenY):
            x=lastindex(X[:i+1:],Y[j])
            y=lastindex(Y[:j+1:],X[i])

            if x!=-1 and y!=-1:
                Z[i][j]=max(Z[x][j],Z[i][y])+1
            elif x!=-1:
                Z[i][j]=Z[x][j]+1
            elif y!=-1:
                Z[i][j]=Z[i][y]+1

            Z[i][j]=max(Z[i][j],Z[i-1][j],Z[i][j-1])

    print(Z[-1][-1])

Python: import sys
import math
import string
import fractions
import random
from operator import itemgetter
import itertools
from collections import deque
import copy
import heapq
from bisect import bisect, bisect_left, bisect_right

MOD = 10 ** 9 + 7
INF = float('inf')
input = lambda: sys.stdin.readline().strip()

sys.setrecursionlimit(10 ** 8)


q = int(input())
for _ in range(q):
    s = input()
    t = input()

    info = deque(deque() for _ in range(100))
    check = []
    for i in range(len(s)):
        info[ord(s[i]) - 97].appendleft(i)
    ans = [INF] * (max(len(s), len(t)) + 10)
    link = [0] * (max(len(s), len(t)) + 10)
    for i in t:
        for l in info[ord(i) - 97]:
            ans[bisect_left(ans, l)] = l
    print(bisect_left(ans, INF))

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

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]


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    pair_num = int(_input[0])

    word_list = list(map(lambda x: x.strip(), _input[1:]))
    # assert len(word_list) == 2 * pair_num
    for k in range(0, len(word_list), 2):
        print(lcs(word_list[k], word_list[k + 1]))

Python: def ask(X,Y):
 cost=[0]
 for j in Y:
  for i in range(len(cost)-1,-1,-1):
   a=X.find(j,cost[i])+1
   if a:
    if i+1<len(cost):
     cost[i+1]=min(cost[i+1],a)
    else:
     cost.append(a)
 return len(cost)-1
 


q=int(input())
Z=[]
for p in range(q):
 X=input()
 Y=input()
 z=ask(X,Y)
 Z.append(z)

for p in range(q):
 print(Z[p])