Understanding the Open Address Method Using Double Hash

#include<stdio.h>
# include <string.h>

using namespace std;
using ll = long long;

#define M1000003
#define L14

char H[M][L]; /* Hash Table*/

int GetChar(charge){
    if(ch=='A')return1;
    else if(ch=='C') return2;
    else if(ch=='G') return3;
    else if(ch=='T') return 4;
    return 0;
}

ll GetKey(charstr[]){
    ll sum = 0, p = 1, i;
    for(i=0;i<strlen(str);i++){
        sum+=p*(GetChar(str[i])));
        p* = 5;
    }
    return sum;
}

int Hash1(ll key) {return key %M;}
int Hash2(ll key) {return(1+(key%(M-1));}

int find(char str[]){
    ll key = GetKey(str);
    intk = 0;
    while(true){
        int hash_index=(Hash1(key)+k*Hash2(key))%M;
        if(strcmp(H[hash_index], str)==0)return1;
        if(strlen(H[hash_index])==0){
            return 0;
        }
        k++;
    }
    return 0;
}

insert(charstr[]){
    ll key = GetKey(str);
    intk = 0;
    while(true){
        ll hash_index=(Hash1(key)+k*Hash2(key))%M;
        if(strcmp(H[hash_index], str)==0)return1;
        if(strlen(H[hash_index])==0){
            strcpy(H[hash_index], str);
            return1;
        }
        k++;
    }
    return 0;
}

int main() {
    inti,n;
    char str [L], com [9];
    for(i=0;i<M;i++)H[i][0]='\0';

    scanf("%d", & n);

    for(i=0;i<n;i++){
        scanf("%s%s",com,str);

        if(com[0]=='i'){
            insert(str);
        } else {
            if(find(str)){
                printf("yes\n");
            } else {
                printf("no\n");
            }
        }
    }

    return 0;
}

sum+=p*(GetChar(str[i])));
p* = 5;