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(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	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] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// 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])
	}
}

C++: #include <iostream>
#include <algorithm>

#define MAX 1000

using namespace std;


int m[MAX + 2][MAX + 2];
int lcs(string x, string y)
{
    for (int i = 0; i <= y.length(); i++)
        for (int j = 0; j <= x.length(); j++)
            m[i][j] = 0;

    for (int i = 1; i <= y.length(); i++) {
        for (int j = 1; j <= x.length(); j++) {
            if (x[j - 1] == y[i - 1]) {
                m[i][j] = m[i - 1][j - 1] + 1;
            } else {
                m[i][j] = max(m[i - 1][j], m[i][j - 1]);
            }
        }
    }

    return m[y.length()][x.length()];
}

int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        string x, y;
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cstdlib>
#include <cmath>
#include<stdio.h>
#include<queue>
#define MAX 1000000000000000000LL
long long inf=1000000007;
using namespace std;
    int H,A[2000001];

int lcs(string X,string Y){
    int  c[1001][1001];
    long long m=X.size();
    long long  n=Y.size();
    int maxl=0;
    X=' '+X;
    Y=' '+Y;
    for(int i=1; i<=m; i++){
        c[i][0]=0;
    }
    for(int i=1; i<=n; i++)c[0][i]=0;
    
    for(int i=1; i<=m; i++){
        for(int j=1; j<=n; j++){
            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]);
            }
            maxl=max(maxl,c[i][j]);
        }
    }
    return maxl;
}
int main(){
    string s1,s2;
    int n;cin>>n;
    for(int i=0; i<n; i++){
        cin>>s1>>s2;
        cout<<lcs(s1,s2)<<endl;
    }
    return 0;

 
}

C++: #include <iostream>
#include <string>
#include <algorithm>
    using namespace std;
int lcs(string x,string y){
    int c[1010][1010];
    int m = x.size();
    int n = y.size();
    int maxl=0;
    x = ' '+x;
    y = ' '+y;
    for (int i=1; i<=m; i++) {
        c[i][0] = 0;
    }
    for(int j=1;j<=n;j++){
        c[0][j] = 0;
    }

    for(int i=1;i<=m;i++){
        for(int j=1;j<=n;j++){
            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]);
            maxl = max(maxl, c[i][j]);
        }
        
    }
    return maxl;
}
int main(){
    int q;
    string x;
    string y;
    scanf("%d",&q);
    for (int i=0; i<q; i++) {
        cin>>x>>y;
        cout<<lcs(x, y)<<endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;

#define MAX 1000

int lcs(string X, string Y) {
    int c[MAX+1][MAX+1];
    int m = X.size();
    int n = Y.size();
    int i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

    for (i = 1 ; i <= m ; i++ ) c[i][0] = 0;
    for (j = 1 ; j <= n ; j++ ) c[0][j] = 0;

    for(i = 1 ; i <= m ; i++ ) {
        for(j = 1 ; j <= n ; j++ ) {
            if (X[i] == Y[j]) {
                c[i][j] = c[i-1][j-1] + 1;
            }else if( c[i-1][j] >= c[i][j-1] ) {
                c[i][j] = c[i-1][j];
            }else {
                c[i][j] = c[i][j-1];
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string x, y;
    

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> x;
        cin >> y;
        cout << lcs(x, y) << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
static const int N = 1000;

int lcs(string X, string Y) {
    int c[N+1][N+1];
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X = ' ' + X; //X[0]???????????????????????\
    Y = ' ' + Y;
    for(int i = 1; i <= m; ++i) {
        c[i][0] = 0;
    }
    for(int j = 1; j <= n; ++j) {
        c[0][j] = 0;
    }

    for(int i = 1; i <= m; ++i) {
        for(int j = 1; j <= n; ++j) {
            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]);
            }
            maxl = max(maxl, c[i][j]);
        }
    }
    return maxl;
}

int main() {
    string s1, s2;
    int n; cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#include <iostream>
#include <math.h>
using namespace std;

int lcs(string x, string y) {
    int _lcs = 0;
    int x_size = x.size();
    int y_size = y.size();
    int dp[x_size + 1][y_size + 1];
    for (int i=0; i <= x_size; i++) {
        dp[i][0] = 0;
    }

    for (int j=0; j <= y_size; j++) {
        dp[0][j] = 0;
    }

    for (int i=1; i <= x_size; i++) {
        for (int j=1; j <= y_size; j++) {
            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[x_size][y_size];
}
int main() {
    int q;
    cin >> q;
    for (int i=0; i < q; i++) {
        string x, y;
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;

int main(){
  
  int q, lcs[1010][1010] = {};
  string a, b;
  
  cin >> q;
  for(int i = 0;i < q;i++){
    cin >> a;
    cin >> b;
    
    for(int r = 0;r < a.size();r++){
      for(int c = 0;c < b.size();c++){
        if(a[r] == b[c]) lcs[r + 1][c + 1] = lcs[r][c] + 1;
        else lcs[r + 1][c + 1] = max(lcs[r + 1][c], lcs[r][c + 1]);
      }
    }
    
    cout << lcs[a.size()][b.size()] << endl;
  }
  
  return 0;
}