Identity · Repeated child replacement

#include <inttypes.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct{int64_t value;}Child;typedef struct{Child *child;}Root;
int main(int argc,char**argv){
    int64_t n=argc>1?atoll(argv[1]):40000000,checksum=0;Root root={malloc(sizeof(Child))};root.child->value=0;
    for(int64_t i=0;i<n;i++){Child*next=malloc(sizeof(*next));next->value=i+1;free(root.child);root.child=next;checksum=(checksum+root.child->value)%1000003;}
    printf("%" PRId64 "\n",checksum);free(root.child);
}

construct Child { let value: Int }
construct Root { state child: Child }
@main {
    let root: Root(child: Child(value: 0))
    state i: Int(0)
    state checksum: Int(0)
    while i < 40000000 {
        root.child: Child(value: i + 1)
        checksum: (checksum + root.child.value) % 1000003
        i: i + 1
    }
    return checksum % 251
}