How to find missing numbers in PHP

PHP method to find missing numbers: 1. Create a php sample file; 2. Check the growth pattern of the sample data; 3. Through "nums[i] == i" or "nums[i] > ; i" method to determine the location of missing values; 4. Find missing numbers by defining the "function missingNumber($nums) {...}" method.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, Dell G3 computer.

How to find missing numbers in PHP?

PHP Calculate the missing numbers from 0 to n-1

The missing numbers from 0 to n-1

A length is All numbers in an ascending sorted array of n-1 are unique, and each number is in the range 0 to n-1. Among the n numbers in the range 0~n-1, there is only one number that is not in the array. Please find this number.

Example 1:

输入: [0,1,3]
输出: 2

Example 2:

输入: [0,1,2,3,4,5,6,7,9]

Output: 8

Solution ideas

Simple binary search, the meaning of the question is clear that all numbers are increasing, and the value range of all numbers is in [0, n-1] and is unique, so we can find such a rule:

As long as nums[i] == i during the query process, then the missing value must be on the right side of i;

If nums[i] > i during the query process, then the missing value must be on the left side; So in the end, just return min as the result.

Code

class Solution {
    /** * @param Integer[] $nums * @return Integer */
    function missingNumber($nums) {
        $min = 0;
        $max = count($nums) - 1;
        while ($min <= $max) {
            $mid = (int)($min + ($max - $min) / 2);
            $mid == $nums[$mid] ? $min = $mid + 1 : $max = $mid - 1;
        }
        
        return $min;
    }
}

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