#include #include #include // In C, it's immediately obvious my python solution is inefficient // For keeping track of the length of sequences // c is a temporary counter, s changes when c reaches a new maximum long int c = 0; long int s = 0; long int collatz(long int seed){ c++; if(seed == 1) return 0; if(seed % 2 == 0) seed = seed / 2; else seed = 3 * seed + 1; collatz(seed); } int main(){ for(long int i = 1; i < pow(10, 6); i++){ c = 0; collatz(i); if(c > s){ s = c; } } printf("The longest sequence has %d numbers \n", s); return 0; }