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])
	}
}

C++: #include<bits/stdc++.h>

using namespace std;


int main() {
    int q;
    cin >> q;

    vector<string> X(q), Y(q);
    int X_size, Y_size;

    vector<int> tmp(3, 0);

    for(int i = 0; i < q; i++) {
        cin >> X[i];
        cin >> Y[i];
    }

    for(int k = 0; k < q; k++) {
        X_size = X[k].size();
        Y_size = Y[k].size();

        // Xのi文字目までとTのj文字目までのLCSの長さdp[i][j]
        vector<vector<int> > dp(X_size+1, vector<int>(Y_size+1, 0));

        // 初期条件
        dp[1][0] = 0, dp[0][1] = 0;

        // dp開始
        for(int i = 1; i <= X_size; i++) {
            for(int j = 1; j <= Y_size; j++) {
                if(X[k][i-1] == Y[k][j-1]) {
                    tmp = {};
                    tmp.push_back(dp[i-1][j-1] + 1);
                    tmp.push_back(dp[i-1][j]);
                    tmp.push_back(dp[i][j-1]);
                    sort(tmp.begin(), tmp.end());
                    dp[i][j] = tmp.back();
                    // dp[i][j] = max({dp[i-1][j-1] + 1, dp[i-1][j], dp[i][j-1]});
                } else {
                    dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
                }
            }
        }

        cout << dp[X_size][Y_size] << endl;
    }

	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

using ll = long long;

// Longest Common Subsequence between X=x_1...x_m and Y=y_1...y_n
// O(mn)
// ALDS_1_10_C: verified
int main(){
    ll Q; cin >> Q;
    for(ll q=0;q<Q;q++){
        string X, Y; cin >> X >> Y;
        ll m = X.size(), n = Y.size();
        vector<vector<ll> > dp(m + 1, vector<ll>(n + 1));
        for(ll i=1;i<=m;i++){
            for(ll j=1;j<=n;j++){
                if(X[i-1] == Y[j-1]){
                    dp[i][j] = max(max(dp[i][j-1], dp[i-1][j]), dp[i-1][j-1] + 1);
                }else{
                    dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
                }
            }
        }
        cout << dp[m][n] << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <utility>
#include <functional>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <cassert>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)

int dp[1001][1001];

int main() {
    int q;
    cin >> q;
    REP(i, q) {
        string s, t;
        cin >> s >> t;
        REP(i, s.size() + 1) REP(j, t.size() + 1) dp[i][j] = 0;
        REP(i, s.size()) {
            REP(j, t.size()) {
                if (s[i] == t[j])
                    dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
                dp[i + 1][j + 1] = dp[i + 1][j];
                dp[i + 1][j + 1] = dp[i][j + 1];
            }
        }
        cout << dp[s.size()][t.size()] << endl;
    }
    return 0;
}

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

using namespace std;

int lcs(string x,string y){
  int m=x.size();
  int n=y.size();
  int c[m+1][n+1];
  for(int i=0;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-1]==y[j-1]) c[i][j]=c[i-1][j-1]+1;
      else c[i][j]=max(c[i-1][j],c[i][j-1]);
    }
  }
  return c[m][n];
}

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<stdio.h>

int strlen(char s[]) {
  int w = 0;
  while (1) {
    if (s[w] == '\0')
      break;
    w++;
  }
  return w;
}

int max(int a, int b, int c){
  int m = a;
  if (m < b)
    m = b;
  if (m < c)
    m = c;
  return m;
}

int main(void){
  int q, xl = 0, yl = 0, h = 0, i = 0, j = 0;
  int d, ans = 0;
  int DP[1001][1001];
  char X[1001], Y[1001];

  for (i = 0; i < 1001; i++) {
    DP[i][0] = 0;
  }
  for (i = 0; i < 1001; i++) {
    DP[0][i] = 0;
  }

  scanf("%d", &q);
  for (h = 0; h < q; h++) {

    scanf("%s", X);
    scanf("%s", Y);
    xl = strlen(X);
    yl = strlen(Y);

    for (i = 1; i <= xl; i++) {
       for (j = 1; j <= yl; j++) {
        if (X[i-1] == Y[j-1])
          d = 1;
        else
          d = 0;
        DP[i][j] = max(DP[i-1][j-1], DP[i-1][j], DP[i-1][j]) + d;
        if(DP[i][j] > ans)
          ans = DP[i][j];
      }
    }
    printf("%d\n", ans);
    ans = 0;
  }
  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 = 0; 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>
using namespace std;
const static int N = 1000;
int dp[N + 1][N + 1];

int lcs(string X, string Y) {
	int max = 0;
	int m = X.size();
	int n  = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;

	for (int i = 1; i <= m; i++)
		dp[i][0] = 0;
	for (int i = 1; i <= n; i++)
		dp[0][i] = 0;

	for (int i = 1; i <= m; i++) {
		for ( int j = 1; j <= n; j++) {
			if (X[i] == Y[j])
				dp[i][j] = dp[i - 1][j - 1] + 1;
			else {
				if (dp[i - 1][j] > dp[i][j - 1])
					dp[i][j] = dp[i - 1][j];
				else
					dp[i][j] = dp[i][j - 1];
			}

			max = (max < dp[i][j]) ? dp[i][j] : max;
		}
	}

	return max;
}

int main(int argc, char const *argv[]) {
	int n;
	cin >> n;


	for (int i = 0; i < n; i++) {
		string X, Y;
		cin >> X >> Y;

		cout << lcs(X, Y) << endl;
	}

	return 0;
}