/*
 * @lc app=leetcode id=852 lang=rust
 *
 * [852] Peak Index in a Mountain Array
 *
 * https://leetcode.com/problems/peak-index-in-a-mountain-array/description/
 *
 * algorithms
 * Easy (70.89%)
 * Total Accepted:    129.3K
 * Total Submissions: 182.3K
 * Testcase Example:  '[0,1,0]'
 *
 * Let's call an array A a mountain if the following properties hold:
 * 
 * 
 * A.length >= 3
 * There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] <
 * A[i] > A[i+1] > ... > A[A.length - 1]
 * 
 * 
 * Given an array that is definitely a mountain, return any i such that A[0] <
 * A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].
 * 
 * Example 1:
 * 
 * 
 * Input: [0,1,0]
 * Output: 1
 * 
 * 
 * 
 * Example 2:
 * 
 * 
 * Input: [0,2,1,0]
 * Output: 1
 * 
 * 
 * Note:
 * 
 * 
 * 3 <= A.length <= 10000
 * 0 <= A[i] <= 10^6
 * A is a mountain, as defined above.
 * 
 * 
 */
impl Solution {
    pub fn peak_index_in_mountain_array(a: Vec<i32>) -> i32 {
        let (mut low, mut high) = (0, a.len() - 1) ; 
        let mut mid;
        while low < high {
            mid = (low + high) / 2;
            // println!("{:?}", (low, mid, high));
            if a[mid] < a[mid + 1] { low = mid + 1; }
            else { high = mid; }
        }
        low as i32
    }
}
// pub structSolution; 
use std::collections::HashMap;
use std::collections::HashSet;
use std::fmt::Debug;
use std::hash::Hash;
use std::iter::FromIterator;

#[allow(dead_code)]
pub fn print_map<K: Debug + Eq + Hash, V: Debug>(map: &HashMap<K, V>) {
    for (k, v) in map.iter() {
        println!("{:?}: {:?}", k, v);
    }
}

#[allow(dead_code)]
pub fn say_vec(nums: Vec<i32>){
	println!("{:?}", nums);
}

#[allow(dead_code)]
pub fn char_frequency(s: String) -> HashMap<char, i32> {
    let mut res:HashMap<char, i32> = HashMap::new(); 
    for c in s.chars(){
        *res.entry(c).or_insert(0) += 1;
    }
    res 
}

#[allow(dead_code)]
pub fn vec_counter(arr: Vec<i32>) -> HashMap<i32, i32> {
    let mut c = HashMap::new(); 
    for n in arr { *c.entry(n).or_insert(0) += 1; }
    c 
}

#[allow(dead_code)]
pub fn vec_to_hashset(arr: Vec<i32>) -> HashSet<i32> {
   HashSet::from_iter(arr.iter().cloned())
}