Question

hello, I'm having trouble understanding the problems below for my Computer science class, please include a work-through and some explanations on how to do it so that I can understand remember how do problems like this on my own.

Thank you very much

WE ARE USING C++

The following project includes the frequency_start_letter function and a few other functions that work with a string array.

Reminder: you could click "Open in Repl.it" on the top right corner to see the project in full screen.

#include <iostream>

#include "library.h"

using namespace std;

int main() {

  string words[100];  //to store up to 100 words

  int num_words = 0;  //to track the number of words in the words array

  //collect and store words into the words arrray.

  //num_words is updated to reflect the words stored

  collect_data(words, num_words, "words.txt");

  cout << "After collection:" << endl;

  print(words, num_words, 5);   //5 indicates the number of value per row

  cout << "Number of words starting with a:\t";

  cout << frequency_start_letter(words, num_words, 'a') << endl;

  string str;

  bool found = false;

  cout << "What word would you like to remove? ";

  cin >> str;

checkpoint

The above Repl project contains the following prototype in the "library.h" file

int count(const string arr[], int size, int len);

The implementation for the above function in the "library.cpp" file simply returns 0. Improve the function implementation to count the number of elements in the array whose length is the same as specified by the len parameter.

Paste your tested function implementation for the count function into the following box.

The above Repl project contains the following prototype in the "library.h" file

bool add(string arr[], int& size, string element);

The implementation for the above function in the "library.cpp" file simply returns false. Improve the function implementation to add the element into the array while keeping it sorted.

Paste your tested function implementation for the add function into the following box.

Paste the function implementation into the following box.

Answer 1

#include <string>

#include <iostream>

using namespace std;

#define ARRAY_SIZE 100

// To count number of words of array having length len and current size = size

// We are putting const before arr[] to make sure that, this function is not modifying the arrray

// Other variables like size and len are called by value, so these changes won't be reflected in main()

int count(const string arr[], int size, int len) {

int count = 0; // Initialize count

for(int i=0; i<size; i++) { // Iterate through array

if(arr[i].size() == len) // To get length of string, use built in function size() of class string. If lengths are matching

count += 1; // increment count

}

return count;

}

// Add element to sorted array arr[] with current size

bool add(string arr[], int& size, string element) {

if((size + 1) >= ARRAY_SIZE) { // Check if we can add to array. i.e. after adding element, new size should be less than total array size

return false; // If new size > total size, then return false, since we can't add to array

}

int left=0 ,right=size-1, pos; // We are doing binary search to find the position to insert the new element. Initialize left=0(first element) and right = size-1(last element)

while (left <= right) { // Loop until left <= right i.e. there is atleast one element in search array

int mid = left + (right - left) / 2; // compute mid. Mid will be leftmost element + current search array size/2. Here current search array

// will be having right - left elements.

if (arr[mid] == element) // Compare element against mid element of array

pos = mid; // If true, update position to insert the new element as mid

if (arr[mid] < element) { // If mid element of array is less than element means we have to do the search in right hand side

left = mid + 1; // we make left = mid + 1 (first element of search array becomes mid+1)

pos = left; // Update pos

}

else {

right = mid - 1; // If mid element was greater, then we have make the search array to the right of mid

pos = right; // Update pos

}

}

pos = pos > 0 ? pos : 0; // If pos is negative, make position to 0. We have to insert into position pos

cout <<"Position to insert is: " << pos << endl;

for(int i = size; i > pos; i--) { // Move all elements after position pos to next position so that we can insert the element

arr[i] = arr[i-1]; // From the last element of array we will shift the element until the position reaches pos

}

arr[pos] = element; // Add new element to position pos in array

size += 1; // Update size. Since call by reference, this value will updated in main() also

return true; // Return true, as we have updated the array.

}

void print_array(const string arr[], int size) { // Display array with size.

for (int i=0; i<size; i++) {

cout << arr[i] << " ";

}

cout << endl;

}

int main() {

int len = 2, c, size=0; // Declare variables

string words [ARRAY_SIZE]; // Declare array with size equals ARRAY_SIZE

// Initialize the array with test data here. Data should be sorted. We are not reading data as mentioned in the question. But this suffices to show the correctness

// of required functions

words[size++] = "abcd"; words[size++] = "befg"; words[size++] = "cest"; words[size++] = "dbc"; words[size++] = "def"; words[size++] = "run"; words[size++] = "to";

c = count(words, size, len); // Find numbers of words in array with length "len" having size no. of strings in it.

cout << "Number of strings with length '" << len << "' : " << c << endl; // Display it

add(words, size, "zen"); // Add test words to array words.

print_array(words, size); // print array after insertion.

add(words, size, "ab");

print_array(words, size);

add(words, size, "dbc");

print_array(words, size);

}

Provided explanation in comments in code.

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