1608. Special Array With X Elements Greater Than or Equal X

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題目敘述

You are given an array nums of non-negative integers. nums is considered special if there exists a number x such that there are exactly x numbers in nums that are greater than or equal to x.

Notice that x does not have to be an element in nums.

Return x if the array is special, otherwise, return -1. It can be proven that if nums is special, the value for x is unique.

Example 1

Input: nums = [3,5] Output: 2 Explanation: There are 2 values (3 and 5) that are greater than or equal to 2.

Example 2

Input: nums = [0,0] Output: -1 Explanation: No numbers fit the criteria for x. If x = 0, there should be 0 numbers >= x, but there are 2. If x = 1, there should be 1 number >= x, but there are 0. If x = 2, there should be 2 numbers >= x, but there are 0. x cannot be greater since there are only 2 numbers in nums.

Example 3

Input: nums = [0,4,3,0,4] Output: 3 Explanation: There are 3 values that are greater than or equal to 3.

解題思路

Solution

class Solution {
    public int specialArray(int[] nums) {
        int n = nums.length;
        for (int x = 0; x <= n; x++) {
            int count = 0;
            for (int num : nums) {
                if (num >= x) {
                    count++;
                }
            }
            if (count == x) {
                return x;
            }
        }
        return -1;
    }
}