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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1201_1300.s1207_unique_number_of_occurrences;

// #Easy #Array #Hash_Table #2022_04_29_Time_2_ms_(82.71%)_Space_42.4_MB_(34.08%)

import java.util.HashMap;
import java.util.Map;

/**
 * 1207 - Unique Number of Occurrences\.
 *
 * Easy
 *
 * Given an array of integers `arr`, return `true` if the number of occurrences of each value in the array is **unique** , or `false` otherwise.
 *
 * **Example 1:**
 *
 * **Input:** arr = [1,2,2,1,1,3]
 *
 * **Output:** true
 *
 * **Explanation:** The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.
 *
 * **Example 2:**
 *
 * **Input:** arr = [1,2]
 *
 * **Output:** false
 *
 * **Example 3:**
 *
 * **Input:** arr = [-3,0,1,-3,1,1,1,-3,10,0]
 *
 * **Output:** true
 *
 * **Constraints:**
 *
 * *   `1 <= arr.length <= 1000`
 * *   `-1000 <= arr[i] <= 1000`
**/
public class Solution {
    public boolean uniqueOccurrences(int[] arr) {
        Map map = new HashMap<>();
        for (int j : arr) {
            if (map.containsKey(j)) {
                map.put(j, map.get(j) + 1);
            } else {
                map.put(j, 1);
            }
        }
        // map for check unique number of count
        Map uni = new HashMap<>();
        for (Integer val : map.values()) {
            if (uni.containsKey(val)) {
                return false;
            } else {
                uni.put(val, 1);
            }
        }
        return true;
    }
}