Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	n := scanInt(sc)
	results := []int{}
	for i := 0; i < n; i++ {
		results = append(results, resolveInstance())
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func resolveInstance() int {
	x, y := scanString(sc), scanString(sc)
	lx, ly := len(x), len(y)
	dp := make([][]int, lx+1)
	dp[0] = make([]int, ly+1)
	for i := 1; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
		dp[i][0] = dp[i-1][0]
		for j := 1; j <= ly; j++ {
			dp[i][j] = dp[i-1][j]
			if dp[i][j] < dp[i][j-1] {
				dp[i][j] = dp[i][j-1]
			}
			if x[i-1] == y[j-1] {
				cL := dp[i-1][j-1] + 1
				if dp[i][j] < cL {
					dp[i][j] = cL
				}
			}
		}
	}
	return dp[lx][ly]
}

const (
	remove = 0 + iota
	match
)

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include<iostream>

int main(){
  int n;
  std::string x,y;
  std::cin>>n;
  int a[1000][1000];

  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++){
	a[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  a[j][k]=a[j-1][k-1]+1;
	}else{
	  if(a[j-1][k]>a[j][k-1]){
	    a[j][k]=a[j-1][k];
	  }else{
	    a[j][k]=a[j][k-1];
	  }
	}
      }
    }
    std::cout<<a[x.size()-1][y.size()-1]<<"\n";
  }
  return 0;
}

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

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string s, std::string t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 0));

  for (int i = 1; i <= s.size(); ++i) {
    for (int j = 1; j <= t.size(); ++j) {
      if (s[i - 1] == t[j - 1]) {
        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];
      }
    }
  }

  return dp[s.size()][t.size()];
}

int main() {
  int q;
  std::string s, t;
  cin >> q;
  for (int i = 0; i < q; ++i) {
    cin >> s >> t;
    cout << lcs(s, t) << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;
const int maxn=1000+10;
int n;
char a[maxn],b[maxn];
int dp[maxn][maxn];
void solve(char *a,char *b)
{

    int la=strlen(a)-1,lb=strlen(b)-1;
    for(int i=0;i<la;i++) dp[i][0]=0;
    for(int i=0;i<lb;i++) dp[0][i]=0;

    for(int i=0;i<la;i++)
    {
        for(int j=0;j<lb;j++)
        {
            if(a[i]==b[j]) dp[i+1][j+1]=dp[i][j]+1;
            else dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1]);
        }

    }
    printf("%d\n",dp[la][lb]);

}
int main()
{
//    freopen("in.txt","r",stdin);
    scanf("%d",&n);
    getchar();
    while(n--)
    {
        fgets(a,sizeof(a),stdin);
        fgets(b,sizeof(b),stdin);
        solve(a,b);
    }

    return 0;
}

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

int lcs(string x,string y);

int main(){
	int n; cin>>n;
	string x,y;
	for(int i=0;i<n;i++){
		cin>>x>>y;
		cout<<lcs(x,y)<<endl;
	}
	cin.get();cin.get();
}

int lcs(string x,string y){
	int m = x.size() , n = y.size();
	x = ' '+x; y = ' '+y;
	int **c;
	c = new int*[m+1]; for(int i=0;i<=m;i++) c[i] = new int[n+1];
	for(int i=0;i<=m;i++) c[i][0] = 0; for(int j=0;j<=n;j++) c[0][j] = 0;
	int maxl = 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]);
		}
	}
	for(int i=0;i<=m;i++) delete [] c[i]; delete [] c;
	return maxl;
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
#include <inttypes.h>
int c[1001][1001] = {0};
/*int LCS(std::string s, std::string t){
    int n, m, c[1001][1001] = {0};
    n = s.size();
    m = t.size();
    int maxlen = 0;
    for(int i = 1; i <= n; i++){
        c[i][0] = 0;
    }
    for(int i = 1; i <= m; i++){
        c[0][i] = 0;
    }
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(s[i - 1] == t[j - 1]){
                c[i][j] = c[i - 1][j - 1] + 1;
            }
            else{
                c[i][j] = std::max(c[i - 1][j], c[i][j - 1]);
            }
            maxlen = std::max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}*/
int main(){
    int N;

    std::cin >> N;
    std::string s1, s2;
    for(int i = 0; i<N; i++){
        std::cin >> s1 >> s2;
        int n, m;
        n = s1.size();
        m = s2.size();
        int maxlen = 0;
        for(int i = 1; i <= n; i++){
            c[i][0] = 0;
        }
        for(int i = 1; i <= m; i++){
            c[0][i] = 0;
        }
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= m; j++){
                if(s1[i - 1] == s2[j - 1]){
                    c[i][j] = c[i - 1][j - 1] + 1;
                }
                else{
                    c[i][j] = std::max(c[i - 1][j], c[i][j - 1]);
                }
                maxlen = std::max(maxlen, c[i][j]);
            }
        }
        std::cout << maxlen << std::endl;
    }
    return 0;
}

C++: #include <stdio.h>
#include <string.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repi(i, n) for(int i = 1; i < n; ++i)

int max(int a, int b) {
  return a > b ? a : b;
}

int main(void) {
  int n;
  scanf("%d", &n);
  rep(i, n) {
    char x[1500], y[1500];
    int h, w;
    scanf("%s", x);
    scanf("%s", y);
    h = strlen(x), w = strlen(y);
    int dp[h][w], len[w], maxs = 0;
    rep(j, h) rep(k, w) dp[j][k] = 0;
    rep(j, w) if(x[0] == y[j]) dp[0][j] = 1, maxs = 1;
    len[0] = 0;
    repi(j, w) len[j] = max(dp[0][j - 1], len[j - 1]);
    repi(j, h) {
      rep(k, w) if(x[j] == y[k]) {
        dp[j][k] = len[k] + 1;
        if(maxs < dp[j][k]) maxs = dp[j][k];
      }
      repi(k, w) len[k] = max(dp[j][k - 1], max(len[k], len[k - 1]));
      /*rep(k, w) printf("%d ", len[k]);
      printf("\n");*/
    }
    /*printf("\n");
    rep(j, h) {
      rep(k, w) printf("%d ", dp[j][k]);
      printf("\n");
    }*/
    printf("%d\n", maxs);
  }
  return 0;
}

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

int lcs(string &X, string &Y) {
  int dp[1000 + 1][1000 + 1];
  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];

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

  return max;
}

int main() {
  int N = 0;
  cin >> N;

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

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

  return 0;
}