/*
 * @lc app=leetcode id=561 lang=rust
 *
 * [561] Array Partition I
 *
 * https://leetcode.com/problems/array-partition-i/description/
 *
 * algorithms
 * Easy (70.99%)
 * Total Accepted:    190.9K
 * Total Submissions: 268.9K
 * Testcase Example:  '[1,4,3,2]'
 *
 * 
 * Given an array of 2n integers, your task is to group these integers into n
 * pairs of integer, say (a1, b1), (a2, b2), ..., (an, bn) which makes sum of
 * min(ai, bi) for all i from 1 to n as large as possible.
 * 
 * 
 * Example 1:
 * 
 * Input: [1,4,3,2]
 * 
 * Output: 4
 * Explanation: n is 2, and the maximum sum of pairs is 4 = min(1, 2) + min(3,
 * 4).
 * 
 * 
 * 
 * Note:
 * 
 * n is a positive integer, which is in the range of [1, 10000].
 * All the integers in the array will be in the range of [-10000, 10000].
 * 
 * 
 */
impl Solution {
    pub fn array_pair_sum(mut nums: Vec<i32>) -> i32 {
        nums.sort(); 
        // let x:i32 = nums.iter().sum();
        nums.iter().step_by(2).sum()
    }
}
// pub structSolution; 
use std::collections::HashMap;
use std::fmt::Debug;
use std::hash::Hash;

#[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 
}