Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

//Util
func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func maxInt(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

func absInt(a int) int {
	if a >= 0 {
		return a
	} else {
		return -a
	}
}

func absFloat64(a float64) float64 {
	if a >= 0 {
		return a
	} else {
		return -a
	}
}

func minFloat64(a, b float64) float64 {
	if a > b {
		return b
	} else {
		return a
	}
}

func str2Int(s string) int {
	n, _ := strconv.Atoi(s)
	return n
}

//Main
var sc = bufio.NewScanner(os.Stdin)
var q int
var X, Y string

func lcs(X, Y string) int {
	lenX := len(X)
	lenY := len(Y)
	dp := make([][]int, lenX+1)
	for i := 0; i < lenX+1; i++ {
		dp[i] = make([]int, lenY+1)
	}

	res := 0
	for i := 1; i < lenX+1; i++ {
		for j := 1; j < lenY+1; j++ {
			if X[i-1] == Y[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
			}
			//fmt.Println(dp)
			res = maxInt(res, dp[i][j])
		}

	}
	return res
}

func main() {
	sc.Split(bufio.ScanWords)
	q = nextInt()

	for i := 0; i < q; i++ {
		X = nextStr()
		Y = nextStr()

		fmt.Println(lcs(X, Y))
	}
}

C++: #include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <unordered_map> //???????????\??¢??°
#include <fstream> //ifstream, ofstream

//#define NDEBUG //NDEBUG???#include <cassert>???????????????????????????????????´???assert?????????????????????????????????NDEBUG?????????????????????????????????????????????
#include <cassert> //assert


using namespace std;

//???????????°??????TEST????????????????????¬???????????????????????????????????¢????????????
#define TEST //*******************************************************************************************************************************************
//?????????????????¨??§?????\????????????????????????????????°?????????????¨???????????????????dout???????????????????????§???????????¬??????????????????????????????????????????
//??????????????????????????????????????????????????????????§?CPU???????£??????????????????§???TLE?????????????????????????????????????????§????????¨???                           ????????????????????????cerr????????£????????????????????????????????????
#ifdef TEST
#define dout cout
#define din cin
#else
stringstream dummy; //???????????°??????dout?????????????????????????????????
#define dout dummy.str(""); dummy.clear(stringstream::goodbit); dummy //dummy?????????????????????????????????????????¨?????¢?????¢???????????????
//???????????¨??????????????????goodbit?????????????????????????????¨???????????´????????????????????????????????¨?????°?????????????????§???????????????????????????????????? http://d.hatena.ne.jp/linden/20060427/p1
#endif

//?¨??????????????????????????????????????????????????????´??????OUTPUTFILE????????????????????¬???????????????????????????????????¢????????????
//#define OUTPUTFILE "output.txt" //*******************************************************************************************************************************************
#ifdef OUTPUTFILE
#define dout outputfile //??¨????????????TLE????????§?????????dout?????¨??¨??????????????¢????????????????????????????????????????????§????¨????????????´??????????????£??????????????????????¨?????????????????????????????????????????????§?????????????????????
ofstream outputfile(OUTPUTFILE);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif

//?¨??????\???????????????????????????????????????????????´??????INPUTFROMTEXTFILE????????????????????¬???????????????????????????????????¢????????????
//#define INPUTFILE "input.txt" //*******************************************************************************************************************************************
#ifdef INPUTFILE
#define din inputfile
ifstream inputfile(INPUTFILE);
#endif


#define disp(A) dout << #A << " = " << (A) << endl
#define disP(A) dout << setw(3) << (A) << " " // << setw(3) ??????????????\????????????
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define dispAll(A,n) dout << #A << " = "; rep(j, 0, (n)) {disP(A[j]);} dout << endl

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef unsigned long long ll;


const int INF = 999;//1e9-1;

int dp[1001][1001] = {0};
pii from[1001][1001];

string X, Y;



int solve(int i, int j) {
//    disp(i); disp(j);
    
    int ans;
    
    if(i<0 or j<0) return 0;
    
    if(dp[i][j]!=0) return dp[i][j];
    
    if(X[i]==Y[j]) {
        ans = solve(i-1,j-1) + 1;
        from[i][j] = make_pair(i-1, j-1);
    } else {
        if( solve(i-1,j) > solve(i,j-1) ) {
            ans = solve(i-1,j);
            from[i][j] = make_pair(i-1, j);
        } else {
            ans = solve(i,j-1);
            from[i][j] = make_pair(i, j-1);
        }
    }
    
    dp[i][j] = ans;

//    //test display
//    dout<<"-------------------------------------\n";
//    dout<<"                ";
//    rep(j,0,Y.size()) disP(j); dout<<endl;
//    dout<<"                ";
//    rep(j,0,Y.size()) disP(Y[j]); dout<<endl;
//    rep(i,0,X.size()) {
//        disP(i); disP(X[i]); dispAll(dp[i], Y.size());
//    }
    
    return ans;
}


int main() {
    int q; din >> q;
    rep(i,0,q) {
        din >> X >> Y;
//        disp(X); disp(Y);
//        dout<<solve(X.size()-1,Y.size()-1)<<endl;
//        
//        rep(i,0,X.size()) {
//            rep(j,0,Y.size()) {
//                dp[i][j]=0;
//                from[i][j] = make_pair(-1, -1);
//            }
//        }
        
        rep(i,0,X.size()+1) {
            rep(j,0,Y.size()+1) {
                dp[i][j]=0;
            }
        }
        
        rep(i,1,X.size()+1) {
            rep(j,1,Y.size()+1) {
                if(X[i-1]==Y[j-1]) {
                    dp[i][j] = dp[i-1][j-1] + 1;
                }
                else {
                    dp[i][j] = max( dp[i-1][j], dp[i][j-1]);
                }
            }
        }
        
//            //test display
//            dout<<"-------------------------------------\n";
//            dout<<"                ";
//            rep(j,0,Y.size()+1) disP(j); dout<<endl;
//            dout<<"                    ";
//            rep(j,1,Y.size()+1) disP(Y[j-1]); dout<<endl;
//            rep(i,0,X.size()+1) {
//                if(i==0) {
//                    disP(i); disP(0); dispAll(dp[i], Y.size()+1);
//                } else {
//                    disP(i); disP(X[i-1]); dispAll(dp[i], Y.size()+1);
//                }
//            }
        
        dout<<dp[X.size()][Y.size()]<<endl;
        
    }
    
    
    
#ifdef INPUTFILE
    inputfile.close();
#endif
    
#ifdef OUTPUTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[1000][1000];
  int j,k;
  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	ans[j][k]=0;
      }
    }
    for(int j=1;j<x.size();j++){
      for(int k=1;k<y.size();k++){
	if(x[j]==y[k]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}