g2401_2500.s2401_longest_nice_subarray.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g2401_2500.s2401_longest_nice_subarray;

// #Medium #Array #Bit_Manipulation #Sliding_Window
// #2022_09_26_Time_4_ms_(87.45%)_Space_70.5_MB_(79.87%)

/**
 * 2401 - Longest Nice Subarray\.
 *
 * Medium
 *
 * You are given an array `nums` consisting of **positive** integers.
 *
 * We call a subarray of `nums` **nice** if the bitwise **AND** of every pair of elements that are in **different** positions in the subarray is equal to `0`.
 *
 * Return _the length of the **longest** nice subarray_.
 *
 * A **subarray** is a **contiguous** part of an array.
 *
 * **Note** that subarrays of length `1` are always considered nice.
 *
 * **Example 1:**
 *
 * **Input:** nums = [1,3,8,48,10]
 *
 * **Output:** 3
 *
 * **Explanation:** The longest nice subarray is [3,8,48]. This subarray satisfies the conditions:
 *
 * - 3 AND 8 = 0.
 *
 * - 3 AND 48 = 0.
 *
 * - 8 AND 48 = 0.
 *
 * It can be proven that no longer nice subarray can be obtained, so we return 3.
 *
 * **Example 2:**
 *
 * **Input:** nums = [3,1,5,11,13]
 *
 * **Output:** 1
 *
 * **Explanation:** The length of the longest nice subarray is 1. Any subarray of length 1 can be chosen. 
 *
 * **Constraints:**
 *
 * *   1 <= nums.length <= 10⁵
 * *   1 <= nums[i] <= 10⁹
**/
public class Solution {
    public int longestNiceSubarray(int[] nums) {
        int ans = 1;
        int left = 0;
        int right = 0;
        while (right < nums.length) {
            for (int i = right - 1; i >= left; i--) {
                if ((nums[i] & nums[right]) != 0) {
                    left = i + 1;
                    break;
                }
                if (i == left) {
                    ans = Math.max(ans, right - left + 1);
                }
            }
            right++;
        }
        return ans;
    }
}