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 <bits/stdc++.h>
using namespace std;
long long dp[1002][1002];
int main() {
  int n;cin>>n;
  for(int i=0; i<n; i++){
  
  string a,b; cin>>a>>b;
  int al=a.size(); int bl=b.size();
  for (int i=0;i<1002;i++){for(int j=0;j<1002;j++){dp[i][j]=0;}}
  for (int j=0;j<al;j++){
  for (int k=0;k<bl;k++){
  if(a[j]==b[k]){dp[j+1][k+1]=dp[j][k]+1;}
  else{dp[j+1][k+1]=max(dp[j+1][k],dp[j][k+1]);}
  }
  }
  cout << dp[al][bl] << endl;
  }
}

C++: #include<iostream>
#include<vector>
#include<string>
using namespace std;
string s1,s2;
int memo[100][100];

int solve(int l1,int l2){
  if(memo[l1][l2] < 0)return memo[l1][l2];
  if(l1 < 0 or l2 < 0)return 0;
  //cout << s1[l1] << s2[l2] << endl;
  if(s1[l1] == s2[l2]){
    return memo[l1][l2] = solve(l1 - 1,l2 - 1) + 1;
  }
  return memo[l1][l2] = max(solve(l1,l2-1), solve(l1-1,l2));
}
int main(){
  int n;
  cin >> n;
  for(int i = 0;i < n;i++){
    fill(*memo,*(memo+100),-1);
    cin >> s1 ;
    cin >> s2;
    cout << solve(s1.length(),s2.length()) - 1 << endl;
  }
}

C++: #include <iostream>
#include <cmath>
#define MAX_NUMBER 1001

using namespace std;

int main () {
  // 最长公共子序列
  int n;
  string x, y;
  int lcs, c[MAX_NUMBER][MAX_NUMBER];

  cin >> n;

  for (int k = 0; k < n; k++) {
    cin >> x;
    cin >> y;

    x = " " + x;
    y = " " + y;
    lcs = 0;
    for (int i = 0; i < MAX_NUMBER; i++)
      for (int j = 0; j < MAX_NUMBER; j++)
        c[i][j] = 0;
    
    for (int i = 1; i < x.length(); i++) {
      for (int j = 1; j < y.length(); 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]);
      }
    }

    cout << c[x.length() - 1][y.length() - 1] << endl;
  }

  return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
char s1[1005];
char s2[1005];
int chang[1005][1005];
int main(){
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%s%s",s1,s2);
        int sl1=strlen(s1);
        int sl2=strlen(s2);
        for(int i=0;i<=sl1;i++){
                chang[i][0]=0;
        }
        for(int i=0;i<=sl2;i++){
                chang[0][i]=0;
        }
        for(int i=1;i<=sl1;i++){
            for(int j=1;j<=sl2;j++){
                if(s1[i]==s2[j]){
                    chang[i][j]=chang[i-1][j-1]+1;
                }
                else {
                    chang[i][j]=max(chang[i-1][j],chang[i][j-1]);
                }
            }
        }
        printf("%d\n",chang[sl1][sl2]);
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define For(I,A,B) for(int I=(A); I < (B); ++I)
int c[1005][1005];
int main()
{
int t;
string p;
cin>>t;
getline(cin,p);
while(t--){

int x,y,z,k=0,l,i,j;
string a,b;

 For(i,0,1005)
 For(j,0,1005)
 c[i][j]=0;

 getline(cin,a);
 getline(cin,b);
 x=a.length();
 y=b.length();

 For(i,1,x+1)
 For(j,1,y+1)
 {
     if(a[i-1]==b[j-1]) c[i][j]=c[i-1][j-1]+1;
     else  c[i][j]=max(c[i-1][j],c[i][j-1]);
 }
    cout<<c[x][y]<<endl;

}

    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include<string.h>
using namespace std;
int LCS(char *x,char *y);
char x[1001], y[1001];
int lcs[1001][1001];
int main()
{
	int q,i,j;

	cin >> q;
	for (i = 0; i < q; i++) {
		cin >> x;
		cin >> y;
		cout << LCS(x, y) << endl;
	}
}

int LCS(char *x, char *y)
{
	int i, j;
	int len_x, len_y;
	len_x = strlen(x);
	len_y = strlen(y);
	for (i = 0; i < len_x; i++) {
		for (j = 0; j < len_y; j++) {
			lcs[i][j] = '\0';
		}
		//cout << endl;
	}
	for (i = 0; i < len_x; i++) {
		if (x[i] == y[0]) {
			lcs[i][0] = 1;
		}
		else {
			lcs[i][0] = 0;
		}
	}
	for (i = 0; i < len_y; i++) {
		if (x[0] == y[i]) {
			lcs[0][i] = 1;
		}
		else {
			lcs[0][i] = 0;
		}
	}

	for (i = 0; i < len_x; i++) {
		for (j = 0; j < len_y; j++) {
			if (x[i] == y[j]) {
				lcs[i][j] = lcs[i - 1][j - 1] + 1;
				//printf("lcs[%d][%d]=%d\n", i, j, lcs[i - 1][j - 1] + 1);
			}
			if (x[i] != y[j]) {
				lcs[i][j] = max(lcs[i - 1][j], lcs[i][j - 1]);
				//printf("lcs[%d][%d]=%d\n", i, j, max(lcs[i - 1][j], lcs[i][j - 1]));
			}
		}
	//cout << endl;

	}
	for (i = 0; i < len_x; i++) {
		for (j = 0; j < len_y; j++) {
			//printf("%d ", lcs[i][j]);
		}
		//cout << endl;
	}
	//cout << "len_x=" << len_x << endl << "len_y=" << len_y << endl;
			
	return lcs[i-1][j-1];
}

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[i]) {
        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 <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>

#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define repi(i,a,b) for(int i = (a); i < (b); i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;

const int INF=1<<29;
const double EPS=1e-9;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int dp[1000][1000];
int main(){
	int n;
	cin>>n;
	while(n--){
		memset(dp, 0, sizeof(dp));
		string str1,str2;
		cin>>str1>>str2;
		//int l =min(str1.length(),str2.length());
		for(int i =0;i <str1.length();i++){
			for(int j =0;j <str2.length();j++){
				if(str1[i]==str2[j]){
					dp[i+1][j+1]=dp[i][j]+1;
				}else{
					dp[i+1][j+1]=max(dp[i][j+1],dp[i+1][j]);
				}
			}
		}
		cout <<dp[str1.length()][str2.length()]<<endl;
	}
	return 0;
}