MushroomPicker

Given non empty, zero indexed array (A) 
A has n integers (1 < n < 100000) 

A represents number of mushrooms growing in a consecutive spots along the road

Given integers k and m

k = spot on the road and m = number of moves

In one move, she moves to an adjacent spot

Goal: Find maximum number of mushrooms (A[i]) in (m) moves

// Solution #1: Picker doesn't switch more than once
// Time Complexity: O(m^2)

function picker(A, k, m){
  var start = k;
  var totalMush = A[k];
  while(A[k-1] > A[k]){
    k--;
    totalMush += A[k]
  }
  k = start;
  while(A[start + 1] > A[start]){
    totalMush += A[k];
    k++;
  }
  return totalMush;
}

// Solution #2: Prefix Sums
function prefix_sums(A){
  n = A.length;
  P = A[0] * (n+1);
  for(var i = 1; i< n+1; i++){
    P[k] = P[k-1] + A[k-1];
  }
  return P;
}

function mushrooms( A, k, m){
  var leng = A.length;
  var result = 0;
  var pref = prefix_sums(A);
  var left_pos, right_pos
  
  var xrange = Math.min(m,k) +1;
  for(var i = 0; i< xrange; i++){
    left_pos = k-p;
    right_pos = Math.min(n-1, Math.max(k, k+m-2*p);
    result = Math.max(result, count_total(pref, left_pos, right_pos))
  }
  
  var 2ndrange = Math.min(m +1 ,n-k);
  for(var j = 0; j< 2ndrange; j++){
    right_pos = k+p;
    left_pos = Math.max(0, Math.min(k, k-(m-2 *p)))
    result = max(result, count_total(pref, left_pos, right_pos))
  }
  return result;
  
}