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Author: jimit105

2144-maximum-difference-between-increasing-elements/README.md

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+<p>Given a <strong>0-indexed</strong> integer array <code>nums</code> of size <code>n</code>, find the <strong>maximum difference</strong> between <code>nums[i]</code> and <code>nums[j]</code> (i.e., <code>nums[j] - nums[i]</code>), such that <code>0 &lt;= i &lt; j &lt; n</code> and <code>nums[i] &lt; nums[j]</code>.</p>
+
+<p>Return <em>the <strong>maximum difference</strong>. </em>If no such <code>i</code> and <code>j</code> exists, return <code>-1</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [7,<strong><u>1</u></strong>,<strong><u>5</u></strong>,4]
+<strong>Output:</strong> 4
+<strong>Explanation:</strong>
+The maximum difference occurs with i = 1 and j = 2, nums[j] - nums[i] = 5 - 1 = 4.
+Note that with i = 1 and j = 0, the difference nums[j] - nums[i] = 7 - 1 = 6, but i &gt; j, so it is not valid.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [9,4,3,2]
+<strong>Output:</strong> -1
+<strong>Explanation:</strong>
+There is no i and j such that i &lt; j and nums[i] &lt; nums[j].
+</pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [<strong><u>1</u></strong>,5,2,<strong><u>10</u></strong>]
+<strong>Output:</strong> 9
+<strong>Explanation:</strong>
+The maximum difference occurs with i = 0 and j = 3, nums[j] - nums[i] = 10 - 1 = 9.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>n == nums.length</code></li>
+	<li><code>2 &lt;= n &lt;= 1000</code></li>
+	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
+</ul>

2144-maximum-difference-between-increasing-elements/solution.py

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+# Approach: Prefix Minimum Value
+
+# Time: O(n)
+# Space: O(1)
+
+class Solution:
+    def maximumDifference(self, nums: List[int]) -> int:
+        n = len(nums)
+        ans, pre_min = -1, nums[0]
+
+        for i in range(1, n):
+            if nums[i] > pre_min:
+                ans = max(ans, nums[i] - pre_min)
+            else:
+                pre_min = nums[i]
+
+        return ans