Write an efficient recursive function that returns the position of *x* in the subvector *v*[*left*..*right*].
The function must return −1
if *x* does not belong to *v*[*left*..*right*] or if *left* > *right*.

**Precondition**

The vector *v* is sorted in strictly increasing order.
Moreover, we have
0 ≤ *left* ≤ size of v
and −1 ≤ *right* < size of v.

**Interface**

C++ | int position(double x, const vector<double>& v, int left, int right); |

C | int position(double x, double v[], int left, int right); |

Java | public static int position(double x, double[] v, int left, int right); |

Python | position(x, v, left, right) # returns int |

position(x: float, v: list, left: int, right: int) -> int |

**Observation**
You only need to submit the required procedure;
your main program will be ignored.

Information

- Author
- Salvador Roura
- Language
- English
- Translator
- Carlos Molina
- Original language
- Catalan
- Other languages
- Catalan
- Official solutions
- C C++ Java Python
- User solutions
- C++ Python