class Solution {    Map
     
       startIndex;    Map
      
        lengths;    Random random;    public Solution(int[] nums) {        random = new Random();        startIndex = new HashMap<>();        lengths = new HashMap<>();        int length = 1;        int start = nums[0];        startIndex.put(nums[0], 0);        for (int i = 1; i < nums.length; i++) {            if (start != nums[i]) {                lengths.put(start, length);                length = 1;                start = nums[i];                startIndex.put(nums[i], i);            } else{                length++;            }        }        lengths.put(start, length);    }        public int pick(int target) {        if (!startIndex.containsKey(target)) {            return 0;        }                return startIndex.get(target) + random.nextInt(lengths.get(target));    }}/** * Your Solution object will be instantiated and called as such: * Solution obj = new Solution(nums); * int param_1 = obj.pick(target); */