#include "chapter1.hpp"

/**
 *  \brief sliding_window_max_sum
 *
 *  Detailed description
 *
 *  \param array The input array
 *  \param len The length of the input array
 *  \param k_len The length of the subarray
 *  \return return int The maximum found in the subarray
 */
int sliding_window_max_sum(int* array, int len, int k_len){
  int current_max = 0;
  int* window_beg = array;
  int* window_end = (array + k_len);
  int previous_beg = 0;
  // initial sum
  for (int i = 0; i < k_len; i++){
    current_max += array[i];
  }
  previous_beg = *window_beg;
  window_beg += 1;
  window_end += 1;

  // iterate window
  int current_sum = current_max;
  while(window_end != (array + len - 1)){
    current_sum = current_sum - previous_beg + *window_end;
    if (current_sum > current_max){
      current_max = current_sum;
    }
    previous_beg = *window_beg;
    window_beg += 1;
    window_end += 1;
  }

  return current_max;
}


/**
 *  \brief sliding_window_shortest_subarray
 *
 *  Find the shortest subarray that is greater than or equal to x.
 *
 *  \param array The intput array
 *  \param len The length of the input array
 *  \param x The threshold to compare to
 *  \return return the length of the shortest subarray
 */
int sliding_window_shortest_subarray(int* array,int len, int x){

  int* window_beg = &array[0];
  int* window_end = &array[1];
  int current_sum = array[0] + array[1];
  int min_len = len;
  int sub_array_len = len;


  while(window_beg != (array + len - 1)){
    if(current_sum < x){
      window_end += 1;
      current_sum += *window_end;
    }
    if (current_sum >= x){
      sub_array_len = window_end - window_beg + 1;
      if(sub_array_len < min_len){
        min_len = sub_array_len;
      }
      current_sum -= *window_beg;
      window_beg += 1;
      if(window_beg > window_end){
        window_end += 1;
        current_sum += *window_end;
      }
    }

  }

  return min_len;
}