Spoj/Longest_common_subsequence.cpp at master · Jaskamalkainth/Spoj · GitHub

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/*
 *
 *    J1K7_7
 *
 */
#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <cstring>
#include <map>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <limits>
using namespace std;
typedef long long          ll;
typedef unsigned long long ull;
typedef long double        ld;
typedef pair<int,int>      pii;
typedef pair<ll,ll>        pll;
typedef vector<int>        vi;
typedef vector<long long>  vll;
#define l(x) 		       (x << 1) + 1
#define r(x) 		       (x << 1) + 2
#define mid(l, r) 	       ((l + r) >> 1)
#define mp                 make_pair
#define pb                 push_back
#define all(a)             a.begin(),a.end()
#define pr(n)              printf("%d",n)
#define s(n)               scanf("%d",&n)
#define debug(x)	       {cerr <<#x<<" = " <<x<<"\n"; }
#define debug2(x, y)       {cerr <<#x<<" = " <<x<<", "<<#y <<" = " <<y <<"\n";}
#define ss                 second
#define ff                 first
#define m0(x) 		       memset(x,0,sizeof(x))
#define snuke(c,itr)       for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
const int mod=1e9+7;

const ll  mx_ll   = numeric_limits<ll> :: max();
const int mx_int  = numeric_limits<int> :: max();

const long double PI = (long double)(3.1415926535897932384626433832795);

inline bool ispow2(int x){return (x!=0 && (x&(x-1))==0);} //0 or 1

int msb(unsigned x){ union { double a; int b[2]; }; a = x; return (b[1] >> 20) - 1023; }

template<class T>
inline void cinarr(T a, int n){ for (int i=0;i<n;++i) cin >> a[i];}

inline ll powmod(ll a,ll b) {ll res = 1; while(b){if(b&1) res = (res*a)%mod;a = (a*a)%mod;b >>= 1;}return res;}

inline ll gcd(ll a,ll b){ll t;while(b){a=a%b;t=a;a=b;b=t;}return a;}
inline ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

inline int nextint(){ int x; scanf("%d",&x); return x; }
inline ll nextll(){ ll x; scanf("%lld",&x); return x; }


string LCS ( string s , string t )
{
	int len_s =  s.length();
	int len_t = t.length();
	int dp[s.length()+1][t.length()+1];
	for(int i = 0; i <= len_s; i++)
	{
		for(int j = 0; j <= len_t; j++)
		{
			if ( i == 0 || j == 0 ) dp[i][j] =  0;
			else if ( s[i-1] == t[j-1] )
				dp[i][j] = dp[i-1][j-1] + 1;
			else
				dp[i][j] = max ( dp[i-1][j] , dp[i][j-1] );
		}
	}
	int len_of_lcs = dp[len_s][len_t];
	//	 return dp[len_s][len_t];   //  Use if only length of LCS is required

	string ans;
	ans.resize(len_of_lcs);

	int i = len_s;
	int j = len_t;
	int id = len_of_lcs;

	while(i > 0 && j > 0)
	{
		if (s[i-1] == t[j-1] )
		{
			ans[id-1] = s[i-1];
			id--;
			i--; j--;
		}
		else if ( dp[i-1][j] > dp[i][j-1] )
			i--;
		else j--;
	}
	return ans;
}
int main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);


	string s , t; cin >> s >> t;

	cout << LCS ( s ,  t).length()<< "\n";
	return 0;
}