title: Lower Insertion Point
signature: lower_insertion_point <- function(arr, n, x) {
source_py: def lower_insertion_point(arr, n, X):
      if (X < arr[0]):
          return 0
      elif (X > arr[(n - 1)]):
          return n
      lowerPnt = 0
      i = 1
      while ((i < n) and (arr[i] < X)):
          lowerPnt = i
          i = (i * 2)
      while ((lowerPnt < n) and (arr[lowerPnt] < X)):
          lowerPnt += 1
      return lowerPnt
source_cpp: int lower_insertion_point(vector<int> arr, int n, int X) {
    if ( X < arr [ 0 ] ) return 0;
    else if ( X > arr [ n - 1 ] ) return n;
    int lowerPnt = 0;
    int i = 1;
    while ( i < n && arr [ i ] < X ) {
      lowerPnt = i;
      i = i * 2;
    }
    while ( lowerPnt < n && arr [ lowerPnt ] < X ) lowerPnt ++;
    return lowerPnt;
  }