Referência para TopCoder Teaching (Luiza)

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

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;

#define TRACE(x) x
#define PRINT(x) TRACE(printf(x))
#define WATCH(x) TRACE(cout << #x << " = " << x << endl;)

#define rep(i,n) for (int i=0; i<n; i++)

const int inf =0x3f3f3f3f;
const double eps = 1e-9;

char s[30] = "qweryuopsdfghjklzxvbm";
int w[20];

void printBm(int x) {
    for (int i=0; i<21; i++)
        if (x&(1<<i)) printf("1");
        else printf("0");
    printf("\n");
}

class Teaching {
public:
   int count( vector <string> words, int K ) {
    for (int i=0; i<words.size(); i++) {
        int bm=0;

        for (int j=0; j<words[i].size(); j++) {
            for (int k=0; s[k]!='\0'; k++)
                if (words[i][j]==s[k])
                    bm|=(1<<k);
        }

        w[i]=bm;
    }

    int maxW=0;
    for (int i=0; i<(1<<21); i++)
        if (__builtin_popcount(i)==K-5) {
            int cnt=0;

            for (int j=0; j<words.size(); j++)
                if ((w[j]&i)==w[j]) ++cnt;
            maxW=max(maxW,cnt);
        }

    return maxW;
   }
};