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Asked: 2026-05-11T01:19:03+00:00

I am trying to resolve Euler Problem 18 -> http://projecteuler.net/index.php?section=problems&id=18 I am trying to

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I am trying to resolve Euler Problem 18 -> http://projecteuler.net/index.php?section=problems&id=18

I am trying to do this with c++ (I am relearning it and euler problems make for good learning/searching material)

#include <iostream>  using namespace std;  long long unsigned countNums(short,short,short array[][15],short,bool,bool);  int main(int argc,char **argv) {      long long unsigned max = 0;     long long unsigned sum;       short piramide[][15] = {{75,0,0,0,0,0,0,0,0,0,0,0,0,0,0},                             {95,64,0,0,0,0,0,0,0,0,0,0,0,0,0},                             {17,47,82,0,0,0,0,0,0,0,0,0,0,0,0},                             {18,35,87,10,0,0,0,0,0,0,0,0,0,0,0},                             {20,4,82,47,65,0,0,0,0,0,0,0,0,0,0},                             {19,1,23,75,3,34,0,0,0,0,0,0,0,0,0},                             {88,2,77,73,7,63,67,0,0,0,0,0,0,0,0},                             {99,65,4 ,28,6,16,70,92,0,0,0,0,0,0,0},                             {41,41,26,56,83,40,80,70,33,0,0,0,0,0,0},                             {41,48,72,33,47,32,37,16,94,29,0,0,0,0,0},                             {53,71,44,65,25,43,91,52,97,51,14,0,0,0,0},                             {70,11,33,28,77,73,17,78,39,68,17,57,0,0,0},                             {91,71,52,38,17,14,91,43,58,50,27,29,48,0,0},                             {63,66,4,68,89,53,67,30,73,16,69,87,40,31,0},                             {4,62,98,27,23,9,70,98,73,93,38,53,60,4,23}};      for (short i = 0;i<15;i++) {         for (short m=0;m<15;m++) {             if (piramide[i][m] == 0)                 break;             sum = countNums(i,m,piramide,15,true,true);             if (sum > max)                 max = sum;             sum = countNums(i,m,piramide,15,true,false);             if (sum > max)                 max = sum;             sum = countNums(i,m,piramide,15,false,true);             if (sum > max)                 max = sum;             sum = countNums(i,m,piramide,15,false,false);             if (sum > max)                max = sum;          }      }     cout << max;     return 0; }   long long unsigned countNums(short start_x,short start_y,short array[][15],short size, bool goright,bool goright2) {     long long unsigned currentSum;      currentSum = array[start_x][start_y];      if (goright) { //go right         if ((start_x + 1) < size)             start_x++;         if ((start_y + 1) < size)             start_y++;     }     else //go down         if ((start_x + 1) < size)             start_x++;      if (goright2) { //still going right         for (short i = start_x, m = start_y;i< size && m < size;i++,m++) {             currentSum += array[i][m];                  }     }     else { //still going down         for (short i = start_x;i<size;i++) {             currentSum += array[i][start_y];                     }     }      return currentSum; }

The countNums function is used to go either down or diagonally. I have tested this function like so:

short a = 0; short b = 0; cout << countNums(a,b,piramide,15,true,true) << endl; cout << countNums(a,b,piramide,15,true,false) << endl; cout << countNums(a,b,piramide,15,false,true) << endl; cout << countNums(a,b,piramide,15,false,false) << endl; return 0;

And it does work (I also changed the function a little so it would print every number it was going through)

But I still don’t get the right result. This goes down and to the right and still goes right (adjacent numbers to the right), goes down and keeps going down (adjacent number to the left). What am I doing wrong here, anyone?

Alastair: It’s simple

long long unsigned countNums(short start_x,short start_y,short array[][15],short size, bool goright,bool goright2);

start_x and start_y are the coords of the array array is the reference to the array size is just the size of the array (it’s always 15) goright is to know if I am going to go down and right or just down goright2 is to know if I am going to continue to go down or going left

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1 Answer

  1. Ok so first off, I’m a little unclear as to what you think the problem is. I can’t parse that second-last sentence at all…

    Secondly you might want to re-think your design here. Think about functions that perform a single discrete task and are not intertwined with the rest of the application (ie read up on ‘tightly coupled and loosely bound’). For me a big warning bell here is the presence of a overly-generic function name countNums with a long list of arguments.

    I think if you were to divide the problem into smaller, more easily comprehensible, chunks you might find the problems a lot easier to find. I know the approach that I would take here but I’m assuming the whole point of the exercise is to help you practice your programming skills, so I’ll just leave it at that…

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