maximum-equal-adjacent-pairs-after-at-most-one-replacement

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Algorithms

You are given a 1-indexed integer array <code>nums</code>.

You can choose two distinct values <code>x</code> and <code>y</code> and perform the following operation at most once:

<ul>
	<li>Replace every occurrence of <code>x</code> in <code>nums</code> with <code>y</code>.</li>
</ul>

Return the maximum possible number of pairs of adjacent elements that are equal after performing the operation.

&nbsp;
Example 1:

<div class="example-block">
Input: nums = [1,2,3,2]

Output: 2

Explanation:

<ul>
	<li>One optimal solution is to choose <code>x = 3</code> and <code>y = 2</code>.</li>
	<li>The resulting array is <code>[1, 2, 2, 2]</code>.</li>
	<li>There are 2 pairs of adjacent elements that are equal: <code>(nums[2], nums[3])</code> and <code>(nums[3], nums[4])</code>.</li>
	<li>Therefore, the answer is 2.</li>
</ul>
</div>

Example 2:

<div class="example-block">
Input: nums = [1,2,1,2,1]

Output: 4

Explanation:

<ul>
	<li>One optimal solution is to choose <code>x = 1</code> and <code>y = 2</code>.</li>
	<li>The resulting array is <code>[2, 2, 2, 2, 2]</code>.</li>
	<li>There are 4 pairs of adjacent elements that are equal: <code>(nums[1], nums[2])</code>, <code>(nums[2], nums[3])</code>, <code>(nums[3], nums[4])</code>, and <code>(nums[4], nums[5])</code>.</li>
	<li>Therefore, the answer is 4.</li>
</ul>
</div>

Example 3:

<div class="example-block">
Input: nums = [1,1,1]

Output: 2

Explanation:

<ul>
	<li>One optimal solution is to perform no operation.</li>
	<li>Thus, the resulting array is <code>[1, 1, 1]</code>.</li>
	<li>There are 2 pairs of adjacent elements that are equal: <code>(nums[1], nums[2])</code> and <code>(nums[2], nums[3])</code>.</li>
	<li>Therefore, the answer is 2.</li>
</ul>
</div>

&nbsp;
Constraints:

<ul>
	<li><code>2 &lt;= nums.length &lt;= 105</code></li>
	<li><code>1 &lt;= nums[i] &lt;= 109</code></li>
</ul>

Weekly Contest 521

weekly-contest-521

maxEqualAdjacentPairs

Staff

Maximum Equal Adjacent Pairs After at Most One Replacement

Array

Hash Table

Counting

Accepted

Wrong Answer

Memory Limit Exceeded

Output Limit Exceeded

Time Limit Exceeded

Runtime Error

Internal Error

Compile Error

Timeout

Restrictions Failed

cangjie

react

vanillajs

You are given a 1-indexed integer array nums.

You can choose two distinct values x and y and perform the following operation at most once:

 * Replace every occurrence of x in nums with y.

Return the maximum possible number of pairs of adjacent elements that are equal after performing the operation.

 

Example 1:

Input: nums = [1,2,3,2]

Output: 2

Explanation:

 * One optimal solution is to choose x = 3 and y = 2.
 * The resulting array is [1, 2, 2, 2].
 * There are 2 pairs of adjacent elements that are equal: (nums[2], nums[3]) and (nums[3], nums[4]).
 * Therefore, the answer is 2.

Example 2:

Input: nums = [1,2,1,2,1]

Output: 4

Explanation:

 * One optimal solution is to choose x = 1 and y = 2.
 * The resulting array is [2, 2, 2, 2, 2].
 * There are 4 pairs of adjacent elements that are equal: (nums[1], nums[2]), (nums[2], nums[3]), (nums[3], nums[4]), and (nums[4], nums[5]).
 * Therefore, the answer is 4.

Example 3:

Input: nums = [1,1,1]

Output: 2

Explanation:

 * One optimal solution is to perform no operation.
 * Thus, the resulting array is [1, 1, 1].
 * There are 2 pairs of adjacent elements that are equal: (nums[1], nums[2]) and (nums[2], nums[3]).
 * Therefore, the answer is 2.

 

Constraints:

 * 2 <= nums.length <= 105
 * 1 <= nums[i] <= 109