国外版

算法题（国外版）/count-good-triplets.html

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+<p>Given an array of integers <code>arr</code>, and three integers&nbsp;<code>a</code>,&nbsp;<code>b</code>&nbsp;and&nbsp;<code>c</code>. You need to find the number of good triplets.</p>
+
+
+
+<p>A triplet <code>(arr[i], arr[j], arr[k])</code>&nbsp;is <strong>good</strong> if the following conditions are true:</p>
+
+
+
+<ul>
+
+	<li><code>0 &lt;= i &lt; j &lt; k &lt;&nbsp;arr.length</code></li>
+
+	<li><code>|arr[i] - arr[j]| &lt;= a</code></li>
+
+	<li><code>|arr[j] - arr[k]| &lt;= b</code></li>
+
+	<li><code>|arr[i] - arr[k]| &lt;= c</code></li>
+
+</ul>
+
+
+
+<p>Where <code>|x|</code> denotes the absolute value of <code>x</code>.</p>
+
+
+
+<p>Return<em> the number of good triplets</em>.</p>
+
+
+
+<p>&nbsp;</p>
+
+<p><strong>Example 1:</strong></p>
+
+
+
+<pre>
+
+<strong>Input:</strong> arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3
+