euler16.c

// Project euler #16

#include <stdio.h>

int digits[1000] = {1};
int len = 1;

void fold() {
    int i, carry = 0;
    for (i = 0; i < len; i++) {
        digits[i] = digits[i] + digits[i] + carry;
        if (digits[i] >= 10) {
            digits[i] -= 10;
            carry = 1;
        } else {
            carry = 0;
        }
    }
    if (carry) {
        digits[i] = carry;
        len++;
    }
}

int sum() {
    int i, r = 0;
    for (i = 0; i < len; i++) {
        r += digits[i];   
    }
    return r;
}

int main() {
    int i;
    for (i = 0; i < 1000; i++) {
        fold();
    }
    printf("%d\n", sum());
}

euler16.pas

program DigitSum;

var
    digits : array[1..1000] of integer;
    len : integer;

procedure fold;
var
    i, carry : integer;
begin
    carry := 0;
    for i := 1 to len do
    begin
        digits[i] := digits[i] + digits[i] + carry;
        if digits[i] >= 10 then
          begin
            digits[i] := digits[i] - 10;
            carry := 1
          end
        else
          carry := 0;
    end;
    if carry > 0 then
    begin
        digits[len+1] := carry;
        len := len + 1
    end
end;

function sum : integer;
var
    i, r : integer;
begin
    r := 0;
    for i := 1 to len do
    begin;
        r := r + digits[i]
    end;
    sum := r
end;

procedure main;
var
    i : integer;
begin
    digits[1] := 1;
    len := 1;
    for i := 1 to 1000 do
        fold();
    writeln(sum())
end;

begin
    main();
end.