高精度整数和整数乘法

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#include <cstdio>
#include <cstring>
#include <algorithm>
#define ms(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int maxn = 100000 + 5;

int n;

int a[maxn], cnt = 1;
void mul(int k){
int g = 0, tmp = 0;
for (int j = 0; j < cnt; j++){
tmp = a[j] * k + g;
a[j] = tmp % 10000;
g = tmp / 10000;
}
while (g){
a[cnt++] = g % 10000;
g /= 10000;
}
}
void print(){
printf("%d", a[cnt - 1]);
for (int i = cnt - 2; i >= 0; i--){
printf("%04d", a[i]);
}
puts("");
}

int main(){
int T; scanf("%d", &T);
while (T--){
scanf("%d", &n);
a[0] = 1; cnt = 1; // init
for (int i = 1; i <= n; i++){
mul(2);
}
print();
}
return 0;
}