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: import sys

def len_lcs(s1, s2):
    """Find length of the longest common sequence(LCS) of strings s1 and s2.
    The complexity is ~MN.

    >>> len_lcs("abc", "abc")
    3
    >>> len_lcs("abcbdaba", "bdcaba")
    5
    """
    len1 = len(s1)
    len2 = len(s2)
    if len1 == 0 or len2 == 0:
        return 0

    primary = [0] * len1
    secondary = [0] * len1

    for i in range(len2):
        for j in range(len1):
            if s1[j] == s2[i]:
                match = 1
            else:
                match = 0
            if j == 0:
                if primary[j] > match:
                    secondary[j] = primary[j]
                else:
                    secondary[j] = match
            else:
                sc1, p1, p2 = secondary[j-1], primary[j-1] + match, primary[j]
                if sc1 > p1:
                    if p1 > p2:
                        secondary[j] = sc1
                    elif p2 > sc1:
                        secondary[j] = p2
                    else:
                        secondary[j] = sc1
                else:
                    if sc1 > p2:
                        secondary[j] = p1
                    elif p1 > p2:
                        secondary[j] = p1
                    else:
                        secondary[j] = p2
                # secondary[j] = max(secondary[j-1], primary[j],
                #                    primary[j-1] + match)

        primary, secondary = secondary, primary

    return primary[len1-1]


def run():
    input()
    s = []
    for line in sys.stdin:
        s.append(line.strip())
    for i in range(0, len(s), 2):
        print(len_lcs(s[i], s[i+1]))


if __name__ == '__main__':
    run()

Python: def solve_L():
    X = input()
    Y = input()
   
    a = len(X)
    b = len(Y)
    c1 = [0 for i in range(b+1)]
    for i in range(a):
        e1 = X[i]
        c2 = c1+[]
        for j in range(b):
            if e1 == Y[j]:
                c1[j+1] = c2[j] + 1
            elif c1[j+1] < c1[j]:
                c1[j+1] = c1[j]
    return c1[-1]
   
n = int(input())
ans = [[] for i in range(n)]
for i in range(n):
    ans[i] = solve_L()
for i in range(n):
  print(ans[i])

Python: def lcs(x, y):

    l1, l2 = len(x), len(y)

    dp = [0] * (l2+1)
    #dp = [[0]*(l2+1) for i in range(l1+1)]

    for i in range(l1):
        prev = dp[:]
        for j in range(l2):
            if x[i] == y[j]:
                dp[j+1] = prev[j] + 1
                #dp[i+1][j+1] = dp[i][j] + 1   
            elif dp[j+1] < dp[j]:
                dp[j+1] = dp[j]
    
    return dp[l2]

N = int(input())
ans = []
for i in range(N):
    x = input()
    y = input()
    ans.append(lcs(x,y))
for i in range(N):
    print(ans[i])

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)

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

        cim1 = c[0]
        for i, xi in enumerate(x, start=1):
            ci = c[i]
            for j, yj in enumerate(y, start=1):
                if xi == yj:
                    ci[j] = cim1[j-1] + 1
                elif cim1[j] >= ci[j-1]:
                    ci[j] = cim1[j]
                else:
                    ci[j] = ci[j-1]
            cim1 = ci

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


main()

Python: def lcs_hs(s1, s2):
    from bisect import bisect_left

    p = []
    append_p = p.append
    for i, c in enumerate(s1):
        j = s2.find(c)+1
        while j:
            append_p((i, -j))
            j = s2.find(c, j)+1

    lis, result = [], 0
    append_lis = lis.append
    for _, y in sorted(p):
        i = bisect_left(lis, -y)
        if i >= result:
            append_lis(-y)
            result += 1
        else:
            lis[i] = -y

    return result


print(*(lcs_hs(input(), input()) for _ in [0]*int(input())), sep="\n")

Python: from collections import defaultdict
INF = 10000
def lcs(s1, s2):
    c = defaultdict(list)
    for i, s in enumerate(s1):
        c[s].append(i)
    for s in set(s2):
        c[s].append(INF)
    def g(li, a):
        for i in li:
            if i >= a:
                return i
        return -1
    dp = []
    for s2_k in s2:
        bgn_idx = 0
        for i, cur_idx in enumerate(dp):
            chr_idx = g(c[s2_k], bgn_idx)
            if chr_idx == INF:
                continue
            dp[i] = min(cur_idx, chr_idx + 1)
            bgn_idx = cur_idx
        else:
            chr_idx = g(c[s2_k], bgn_idx)
            if chr_idx != INF:
                dp.append(chr_idx + 1)
    return len(dp)
def solve():
    N = int(input())
    for _ in range(N):
        x = input()
        y = input()
        print(lcs(x, y))

Python: def lcs(s1_raw, s2_raw):
    dp = []
    for s2 in s2_raw:
        start = 0
        for i, cnt in enumerate(dp):
            index = s1_raw.find(s2, start) + 1
            if not index:
                break
            else:
                dp[i]  = min(cnt , index)
                start = cnt
        index = s1_raw.find(s2, start) + 1
        if index:
            dp.append(index)
    return len(dp)


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

Python: a=''
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]
 a+=f'\n{len(z)}'
print(a[1:])