CS210 - Algorithms and Data Structures I

Department of Computer Science, NUIM



T Naughton, NUIM

Lab Sheet 1



Problem 1.1



int findHighest(int list[]) {

  /* This function returns the index of the largest int in list.

  ** If there are multiple occurances of this int we return the

  ** last occurance. If the list has no elements, return -1.

  */



  int highestindex; // result

  int counter;      // array iterator



  if (list.length = 0) {

    highestindex = -1; // if list is empty...



  } else {



    highestindex = 0; // assume first is highest

    counter = 1;      // start looking from the second element



    while (counter < list.length) {

      if (list[counter] >= list[highestindex]) {

        highestindex = counter;

      }

      counter++;

    }



  }



  return highestindex;

} 







Problem 1.2



void findDuplicates(int list[]) {

  /* This function prints out the indexes of the first two duplicates

  ** found in list. The user is notified if no duplicates are found.

  */



  int counter;   // array iterator

  int pdup;      // a possible duplicate

  boolean found; // have we found duplicates yet?



  // check each list element in turn...

  counter = 0;

  found = false;

  while ((counter < (list.length-1)) && (!found)) {

    pdup = counter+1;

    while ((pdup < list.length) && (!found)) {

      if (list[pdup] == list[counter]) {

        found = true;

      }

      pdup++;

    }

    counter++;

  }



  if (found) {

    println("Duplicates found at indexes " + (counter-1) + " and " + (pdup-1) + '.');

  } else {

    println("No duplicates found.");

  }

} 







Problem 1.3



void findClosestTo10(int list[]) {

  /* This function prints out the index of the element in list

  ** that has a value closest to 10. If multiple such values exist,

  ** the first one found is printed out.

  */



  int counter;

  int cindex; // index with closest value to 10

  int cval;   // difference between cindex's value and 10



  if (list.length == 0) {

    println("List is empty.");



  } else {



    cindex = 0;   // assume it's the first element

    cval = Math.abs(list[cindex] - 10);

    counter = 1;  // start searching from the second element

    while (counter < list.length) {

      if ( Math.abs(list[counter] - 10) < cval) {

        cindex = counter;

        cval = Math.abs(list[counter] - 10);

      }

      counter++;

    }

    println("The value at index " + cindex + " is closest to 10.");

  }

}