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 <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) for(int i=0;i < (n);i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define SCANF(i) int i;scanf("%d",&i)
typedef long long ll;
using namespace std;
using P = pair<int,int>;
const long long INF = 1LL << 60;
const int IINF=100000000;
const int MOD = (int)1e9 + 7;
//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    //sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
vector<int> dx={1,0,-1,0};vector<int> dy={0,-1,0,1};

signed main () {
    int n;cin >> n;
    REP(i,n){
        string s,t;cin >> s >> t;
        int slen=s.length();int tlen=t.length();
        vector<vector<int>> lcm(slen+1,vector<int>(tlen+1,0));
        REP(i,s.length())REP(j,t.length()){
            if(s[i]==t[j]){
                lcm[i+1][j+1]=max({lcm[i][j+1],lcm[i+1][j],lcm[i][j]+1});
            }
            lcm[i+1][j+1]=max({lcm[i+1][j+1],lcm[i+1][j],lcm[i][j+1]});
        }
        cout << lcm[slen][tlen] << endl;
    }

}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrep1(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;


int dp[1000][1000];

int getLCS(string* s1, string* s2, int s1i, int s2i)
{
	int ret;
	int cand1, cand2;

	if (s1i < 0 || s2i < 0) {
		return 0;
	}
	else if (dp[s1i][s2i] != -1) ret = dp[s1i][s2i];
	else if ((*s1)[s1i] == (*s2)[s2i]) {
		ret = getLCS(s1, s2, s1i - 1, s2i - 1) + 1;
	}
	else {
		cand1 = getLCS(s1, s2, s1i, s2i - 1);
		cand2 = getLCS(s1, s2, s1i - 1, s2i);
		ret = max(cand1, cand2);
	}
	dp[s1i][s2i] = ret;

	return ret;
}

int main()
{
	int q;
	int ans;
	string s1, s2;

	cin >> q;
	rep(i, q) {
		rep(j, 1000) {
			rep(k, 1000) dp[j][k] = -1;
		}
		cin >> s1 >> s2;
		ans = getLCS(&s1, &s2, s1.length() - 1, s2.length() - 1);
		cout << ans << endl;
	}

	return 0;
}