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

#define WIDTH   50
#define HEIGHT 100

void rev(char* str){
    int len = strlen(str), i=0;

    while(i < (len - i - 1)){
        str[i] ^= str[len - i - 1];
        str[len - i - 1] ^= str[i];
        str[i] ^= str[len - i - 1];
        i++;
    }
}

void add(char* a, char* b/*, char* answer*/){
    int     sum=0, carry=0, width=strlen(a)+1, i,j;
    char*   answer = malloc(width);

    for(i=0; i<width-1; i++){
        sum = (a[width-2-i]-48) + (b[width-2-i]-48) + carry;
        carry = 0;
        if(sum > 9){
            carry = 1;
            sum-=10;
        }
        answer[i] = sum+48;
    }

    if(carry) answer[i++] = carry+48;
    answer[i]= 0;

    rev(answer);
    memcpy(a,answer,strlen(answer));
    a[strlen(a)+1] = 0;
    free(answer);
}

int main(){
    char    arr[HEIGHT][WIDTH+2], tempAns[WIDTH+1];
    int     i = 0, j = 0, size = 0, carry = 0;
    FILE    *fp = fopen("../sources/files/p13num.txt","r");

    if(!fp) return 1;

/*load array with numbers*/
    do{
        while(fgets(arr[i],WIDTH+2,fp)){
            j=0;
            while(arr[i][j]!=0&&arr[i][j]!=0x0d)j++;
            arr[i][j]=0;
            i++;
        }
    } while(!feof(fp));

//set tempAns as all 0s
    memset(tempAns,'0',WIDTH);
    tempAns[WIDTH] = 0;

    for(i=0;i<5;i++){
        add(tempAns,arr[i]);
        printf("%i:\t%s\n",i,tempAns);
    }

/*Finish*/
    FILE *ofp = fopen("../sources/files/13out.txt","w");
    if(ofp) fprintf(ofp,"%s", arr[i]);

    fclose(fp);
    fclose(ofp);
    return 0;
}