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 <string>
#include <cstdio>
#include <vector>
#include <queue>
#include <map>
using namespace std;

bool findSubStr(string& shortword, vector<vector<int> >& charMap) {
	int i,j;
	j=0;
	for(i=0; i<(int)shortword.size(); ++i) {
		if(charMap[shortword[i]-'a'].empty()) return false;
		auto itr=charMap[shortword[i]-'a'].begin();
		while(itr!=charMap[shortword[i]-'a'].end()) {
			if(*itr<j) {
				++itr;
			} else {
				break;
			}
		}
		if(itr==charMap[shortword[i]-'a'].end()) return false;
		j=*itr;
	}
	return true;
}

int longestSQ(string& shortword, string& longword) {
	int i,j;
	string tempstr,prestr;
	vector<vector<int> > charMap(26);
	queue<string> targetword;
	map<string,bool> inqueue;
	for(i=0; i<(int)longword.size(); ++i) {
		charMap[longword[i]-'a'].push_back(i);
	}
	targetword.push(shortword);
	while(!targetword.empty()) {
		tempstr=targetword.front();
		if(findSubStr(tempstr,charMap)) return (int)tempstr.size();
		j=(int)tempstr.size();
		for(i=0; i<j; ++i) {
				tempstr=targetword.front();
				if(i==0 || tempstr[i]!=tempstr[i-1]) {
					tempstr.erase(tempstr.begin()+i);
					if(inqueue.find(tempstr)==inqueue.end()) {
						targetword.push(tempstr);
						inqueue[tempstr]=true;
					}
				}
		}
		targetword.pop();
	}
	return 0;
}

int main() {
	int i,q;
	cin >> q;
	string wordA,wordB;
	for(i=0; i<q; ++i) {
		cin >> wordA >> wordB;
		if(wordA.size()<wordB.size()) {
			printf("%d\n",longestSQ(wordA,wordB));
		} else {
			printf("%d\n",longestSQ(wordB,wordA));
		}
	}
	return 0;
}

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

int memo[1001][1001];
string s,t;

int dfs(int i, int j)
{
    if(i == 0 || j == 0) return 0;
    
    if(memo[i][j] != -1)return memo[i][j];
    
    int res = 0;
    
    if(s[i-1] == t[j-1]) res = dfs(i-1, j-1) + 1;
    else {
        res = max(dfs(i - 1, j), dfs(i, j - 1));
    }
    return memo[i][j] = res;
}

int main()
{
    int n;
    cin >> n;
    for(int i = 0; i < n; ++i){
        cin >> s >> t;
        fill((int*)memo, (int*)(memo + (int)max(s.size(), t.size()) + 1), -1);
        cout << dfs(s.size(), t.size()) << endl;
    }
}

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

using namespace std;

int lic(string X,string Y) {
	int c[1001][1001];
	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 = 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 X, Y;
	int n;
	cin >> n;
	for (int i = 0;i < n;i++) {
		cin >> X >> Y;
		cout << lic(X, Y)<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
	int m = strlen(s1), n = strlen(s2);
	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 (s1[i] == s2[j])
				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()
{
	char s1[maxx], s2[maxx];
	int t;
	cin >> t;
	getchar();
	for (int i = 0; i < t; i++) {
		cin.getline(s1,1010);
		cin.getline(s2,1010);
		printf("%d\n", lcs(s1, s2));
	}

	return 0;
}