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<stdio.h>
#include<string.h>

#define MAX 1010
#define max(a,b) ((a<b)?b:a)

char s[MAX], t[MAX];
int dp[MAX][MAX],path[MAX][MAX];

int LCS() {
  int n = strlen(s);
  int m = strlen(t);
  memset(dp,0,sizeof dp);
  int i,j,maxi=0;
  for(i=0;i<n;i++) {
    for(j=0;j<m;j++) {
      if( i ) dp[i][j] = max(dp[i][j],dp[i-1][j]);
      if( j ) dp[i][j] = max(dp[i][j],dp[i][j-1]);
      if( s[i] == t[j] ) {
	dp[i+1][j+1] = max(dp[i+1][j+1],dp[i][j]+1);
	maxi = max(maxi,dp[i+1][j+1]);
      }
    }
  }
  return maxi;
}

int main() {
  int n,i;
  scanf("%d",&n);
  for(i=0;i<n;i++) {
  scanf(" %s",&s[0]);
  scanf(" %s",&t[0]);
  printf("%d\n",LCS());
  }
  return 0;
}

C++: //
// Created by 李青坪 on 2018/10/29.
//

#include <cstdio>
#include <algorithm>
#include <string>
#include <iostream>

#define MAXN 150
#define MAXLEN 1000
using namespace std;

int c[MAXLEN+1][MAXLEN+1];

int getSubsequence(string x, string y){
    int i = 0, j = 0;
    while (i <= x.length()){
        while (j <= y.length()){
            if (i == 0 || j ==0){
                c[i][j] = 0;
            } else if (x[i-1] == y[j-1]){
                c[i][j] = c[i-1][j-1] + 1;
            } else if (x[i-1] != y[j-1]){
                c[i][j] = max(c[i-1][j], c[i][j-1]);
            }
            ++j;
        }
        ++i;
        j = 0;
    }
    return c[x.length()][y.length()];
}

int main(){
    int n;
    scanf("%d", &n);
    string x, y;
    for (int i = 0; i < n; ++i) {
        cin >> x >> y;
        printf("%d\n", getSubsequence(x, y));
    }

}
/*
3
abcbdab
bdcaba
abc
abc
abc
bc
 */

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[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 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 <stdio.h>
#include <string.h>
#include <vector>
#include <algorithm>
#include <string>
#pragma warning(disable : 4996)

#define MAX_L 1000

int DP[MAX_L+1][MAX_L+1];

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

int main(void) {
	int n;
	scanf("%d", &n);
	char X[MAX_L + 1];
	char Y[MAX_L + 1];
	for (int i = 0; i < n; ++i) {
		scanf("%s", &X[0]);
		scanf("%s", &Y[0]);
		int xl = strlen(X);
		int yl = strlen(Y);

		for (int j = 0; j < yl; ++j) {
			for (int i = 0; i < xl; ++i) {
				if (X[i] == Y[j]) {
					DP[j + 1][i + 1] = DP[j][i] + 1;
				}
				else {
					DP[j + 1][i + 1] = max(DP[j][i + 1], DP[j + 1][i]);
				}
			}
		}
		printf("%d\n", DP[yl][xl]);

	}

	return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#define N 1000
using namespace std;

int ans[N+1][N+1];

int deal(string s1,string s2){
    int maxl=-1;

    for(int i=0;i<s1.length();i++){
        ans[i][0]=0;
    }
    for(int j=0;j<s2.length();j++){
        ans[0][j]=0;
    }
    for(int i=1;i<s1.length();i++){
        for(int j=1;j<s2.length();j++){
            if(s1[i]==s2[j]){
                ans[i][j]=ans[i-1][j-1]+1;
            }else{
                ans[i][j]=max(ans[i-1][j],ans[i][j-1]);
            }
            maxl=max(maxl,ans[i][j]);
        }
    }
    return maxl;
}

int main(){
    int n;
    string s1,s2;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>s1>>s2;
        s1=" "+s1;
        s2=" "+s2;
        cout<<deal(s1,s2)<<endl;
    }
    return 0;
}

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

#define MAX 1000

int lcs(string x, string y) {
  int c[MAX + 1][MAX + 1];
  int m = x.size();
  int n = y.size();
  int maxl = 0;
  x = ' ' + x;
  y = ' ' + y;
  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 s1, s2;
  int q;
  cin >> q;

  for ( int i = 0; i < q; i++ ) {
    cin >> s1 >> s2;
    cout << lcs(s1, s2) << endl;
  }

  return 0;
}