欧拉筛分解质因子板子

 int p[N], pe[N], primes[N], cnt;
 
 void init() {
     for (int i = 2; i < N; i++ ) {
         if(!p[i]) p[i] = i, pe[i] = i, primes[++ cnt] = i;
         for (int j = 1; j <= cnt && i * primes[j] < N; j++ ){
             p[i * primes[j]] = primes[j];
             if(p[i] == primes[j]) {
                 pe[i * primes[j]] = pe[i] * primes[j];
                 break;
             } else pe[i * primes[j]] = primes[j];
         }
     }   
 }


vector<int> v;
     
     while(t > 1) {
         v.push_back(p[t]);
         int pp = p[t];
         while(t % pp == 0) t /= pp;//如果需要统计质因子个数在这个操作下可以开map或者桶来统计
     }