c++ - How to avoid SEGMENTATION ERROR for the code below? -

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i'm getting segmentation error code below. solution the spoj problem "coins".

i went through how avoid sigsegv? , made sure not use uninitialized pointers, not access out of memory etc (given n ≤ 109).

i know array a[1000000000] lead stack overflow, used std::map. std::map ever lead stack overflow? wrong code?

#include <iostream> #include <cstring> #include <algorithm> #include <cstdio> #include <cmath> #include <map>  using namespace std;  map<unsigned long long int, unsigned long long int> a;  unsigned long long int dp(unsigned long long int n) {       if (a.find(n) == a.end())       a[n] = dp(n/2) + dp(n/3) + dp(n/4);     return a[n]; }  int main() {     (unsigned long long int = 1; <= 24; i++) {         a[i] = i;         if (i == 12 || == 24)            a[i] = + 1;     }      unsigned long long int n = 0;     cin >> n;      while (!feof(stdin)) {         printf("%llu\n", dp(n));         cin >> n;     } }

you sigsegv on dp(0) call. causes infinite recursion.

by way, solution wrong, example answer 24 not 25. try avoid magic constants, enough set a[0] = 0 , make more accurate dp function:

uint32_t dp(uint32_t n) {     if (a.find(n) == a.end())         a[n] = max(n, dp(n / 2) + dp(n / 3) + dp(n / 4));      return a[n]; }

as can seen above, 32-bit type enough store possible answer.


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