import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

/**

* Author : WindAsMe

* File : RandomSolution.java

* Time : Create on 18-9-7

* Location : ../Home/JavaForLeeCode2/RandomSolution.java

* Function : LeetCode No.398

*/

public class RandomSolution {

static class Solution {

private Map<Integer, List<Integer>> map;

public Solution(int[] nums) {

this.map = new HashMap<>();

for (int i = 0; i < nums.length; i++) {

if (map.get(nums[i]) == null) {

List<Integer> list = new ArrayList<>();

list.add(i);

map.put(nums[i], list);

} else {

List<Integer> list = map.get(nums[i]);

list.add(i);

map.put(nums[i], list);

}

}

}

public int pick(int target) {

List<Integer> list = map.get(target);

return list.get((int) (Math.random() * list.size()));

}

public void occur() {

for (Map.Entry<Integer, List<Integer>> entry : map.entrySet()) {

System.out.println(entry.getKey() + " -> " + entry.getValue().toString());

}

}

}

public static void main(String[] args) {

int[] nums = {1,2,3,3,3};

Solution s = new Solution(nums);

System.out.println(s.pick(3));

}

}