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<vector>
#include<string>
using namespace std;
const int NIL = -1;
void SearchMaxSubString(string & a,string & b,
						vector<vector<int> > & maxlen,
						int s,
						int t)
{
	int lengthAB = 0;
	if (a[s] == b[t]) {
		lengthAB++;
		if ((s+1) < (int)a.size() && (t+1) < (int)b.size()) {
			if (maxlen[s+1][t+1] == NIL) {
				SearchMaxSubString(a,b,maxlen,s+1,t+1);
			}
			lengthAB += maxlen[s+1][t+1];
		}
		maxlen[s][t] = lengthAB;
	}
	else {
		int lengthA = 0;
		int lengthB = 0;
		if ((s+1) < (int)a.size()) {
			if (maxlen[s+1][t] == NIL) {
				SearchMaxSubString(a,b,maxlen,s+1,t);
			}
			lengthA = maxlen[s+1][t];
		}
		if ((t+1) < (int)b.size()) {
			if (maxlen[s][t+1] == NIL) {
				SearchMaxSubString(a,b,maxlen,s,t+1);
			}
			lengthB = maxlen[s][t+1];
		}
		maxlen[s][t] = std::max(lengthA,lengthB);
	}
}

int main(){
	int n;
	cin >> n;
	for(; n > 0; --n) {
		string a,b;
		cin >> a >> b;
		vector<vector<int> > maxlen;
		maxlen.resize(a.size());
		for(unsigned int i=0;i<a.size();++i) {
			maxlen[i].resize(b.size());
			for(unsigned j=0;j<maxlen[i].size();++j){
				maxlen[i][j] = NIL;
			}
		}
		SearchMaxSubString(a,b,maxlen,0,0);
		cout << maxlen[0][0] << std::endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
int main(){
  int q;
  std::cin>>q;
  int i,j,k;
  std::string x,y;
  int a[1001][1001];
  int knum[q];
  for(i=0; i<1001; i++){
    for(j=0; j<1001; j++){
      a[i][j]=0;
    }
  }
  for(k=0; k<q; k++){
    std::cin>>x;
    std::cin>>y;
    for(i=1; i<x.size()+1; i++){
      for(j=1; j<y.size()+1; j++){
	if(x[i-1]==y[j-1]){
	  a[i][j]=a[i-1][j-1]+1;
	}else{
	  if(a[i-1][j]>a[i][j-1]){
	    a[i][j]=a[i-1][j];
	  }else{
	    a[i][j]=a[i][j-1];
	  }
	}
      }	
    }
    knum[k]=a[x.size()][y.size()];
  }
  for(k=0; k<q; k++){
    std::cout<<knum[k]<<"\n";
  }
  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;
    Y = ' ' + Y;
    for (int i = 1; i <= m; i++) c[i][0] = 0;
    for (int j = 0; 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>
using namespace std;
typedef long long ll;
//template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
//template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
 
/* attention
    long longのシフト演算には気をつけよう
    タイポした時のデバッグが死ぬほどきつくなるので変数名は最低3字くらい使った方がいいかも
*/

int lcm(string s, string t, vector<vector<int>> dp){
    int m = s.size();
    int n = t.size();
    int maxl = 0;
    s = " " + s;
    t = " " + t;
    for(int i=0; i<=m; i++) dp[i][0] = 0;
    for(int j=0; j<=n; j++) dp[0][j] = 0;

    for(int i=1; i<=m; i++){
        for(int j=1; j<=n; j++){
            if(s[i] == t[j]) dp[i][j] = dp[i-1][j-1]+1;
            else dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            maxl = max(maxl, dp[i][j]);
        }
    }

    return maxl;
}

int main(){
    vector<vector<int>> dp(1001, vector<int>(1001, 0));

    int n; cin >> n;
    for(int i=0; i<n; i++){
        string s, t; cin >> s >> t;
        cout << lcm(s, t, dp) << endl;
    }
}

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;
	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<iostream>
#include<string>
#include<algorithm>
using namespace std;

int lcs(string str1, string str2) {
	int n1 = str1.size();
	int n2 = str2.size();
	int A[n1 + 1][n2 + 1];
	for (int i = 0; i <= n1; i++) A[i][0] = 0;
	for (int j = 1; j <= n1; j++) A[0][j] = 0;

	for (int i = 1; i <= n1; i++) {
		for (int j = 1; j <= n2; j++) { 
			if (str1[i - 1] == str2[j - 1]) {
				A[i][j] = A[i - 1][j - 1] + 1; 
			} else {
				A[i][j] = max(A[i - 1][j], A[i][j - 1]); 
			}
		}
	}
	return A[n1][n2];
}

int main() {
	int n;
	string str1, str2;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << endl;
	}
	return 0;
}