我的代码为什么没超125MB内存呢？？

4*5e7+10=200MB,1e8=100MB,总共300+MB啊，我提交后显示我才用了110+MB，这是什么原理

int prime[50000010], a, b, n = 1, k;
char s[15];
bool isprime[100000010];

#include <bits/stdc++.h>
using namespace std;
// const int MOD = 1e9 + 7;
int prime[50000010], a, b, n = 1, k;
char s[15];
bool isprime[100000010];
void get_prime() {
  memset(isprime, 1, sizeof(isprime));
  isprime[1] = 0;
  for (int i = 2; i <= b; ++i) {
    if (isprime[i]) prime[n++] = i;
    for (int j = 1; j < n && i * prime[j] <= b; ++j) {
      isprime[i * prime[j]] = 0;
      if (i % prime[j] == 0) break;
    }
  }
}
bool judge(int x) {
  k = 0;
  while (x) {
    s[k++] = x % 10;
    x /= 10;
  }
  int i = 0, j = k - 1;
  while (i < j)
    if (s[i] != s[j])
      return false;
    else
      ++i, --j;
  return true;
}
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  cin >> a >> b;
  get_prime();
  int i = lower_bound(prime, prime + n, a) - prime;
  for (; prime[i] <= b && i < n; ++i) {
    if (judge(prime[i])) cout << prime[i] << endl;
  }
  return 0;
}