Uva 910, TV game

Main.C

#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);

using namespace std;

#define PI acos(-1)
#define sqr(x) ((x) * (x))
#define PB push_back
#define MP make_pair
#define F first
#define S second
#define ALL(c) (c).begin(), (c).end()
#define SIZE(c) (int)(c).size()
#define REP(i, a, b) for (int i = int(a); i <= int(b); i++)
#define REPD(i, a, b) for (int i = int(a); i >= int(b); i--)

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<double,double> dd;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef map<int,int> mii;
typedef set<int> si;

const int MAXN=26, MAXM=30;

bool s[MAXN]={false};
vii g;

ll dp[MAXN][MAXM+1]={{0}}; //# ways to win from city i, with j moves left to go

int m, n;

#define PROD //clocking off
int main() {
#ifndef PROD
clock_t stop_s,start_s;
start_s=clock();
#endif
	
	while(cin >> n) {
		g.resize(n+1);
		REP(i, 0, MAXN-1) { s[i]=false; REP(j, 0, MAXM) { dp[i][j]=0; } }

		char x, y, z, d;
		REP(i, 1, n) {
			cin >> x >> y >> z >> d;
			int v=x-'A';

			g[v].F= y-'A';
			g[v].S= z-'A';
			if(d == 'x') { s[v]=true; } else { s[v]= false; }
		}

		cin >> m;

		REP(i, 0, n-1) { if(s[i]) { dp[i][0]=1; }}
		REP(i, 1, m) { REP(j, 0, n-1) { 
			dp[j][i] += dp[g[j].F][i-1] + dp[g[j].S][i-1];
		}}

		cout << dp[0][m] << endl;
	}

#ifndef PROD
stop_s=clock();
cout << "time: " << (stop_s-start_s)/double(CLOCKS_PER_SEC)*1000 << endl;
#endif
	return 0;
}