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"content": "<p>You are given an integer array <code>matchsticks</code> where <code>matchsticks[i]</code> is the length of the <code>i<sup>th</sup></code> matchstick. You want to use <strong>all the matchsticks</strong> to make one square. You <strong>should not break</strong> any stick, but you can link them up, and each matchstick must be used <strong>exactly one time</strong>.</p>\n\n<p>Return <code>true</code> if you can make this square and <code>false</code> otherwise.</p>\n\n<p> </p>\n<p><strong>Example 1:</strong></p>\n<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2021/04/09/matchsticks1-grid.jpg\" style=\"width: 253px; height: 253px;\" />\n<pre>\n<strong>Input:</strong> matchsticks = [1,1,2,2,2]\n<strong>Output:</strong> true\n<strong>Explanation:</strong> You can form a square with length 2, one side of the square came two sticks with length 1.\n</pre>\n\n<p><strong>Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> matchsticks = [3,3,3,3,4]\n<strong>Output:</strong> false\n<strong>Explanation:</strong> You cannot find a way to form a square with all the matchsticks.\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 <= matchsticks.length <= 15</code></li>\n\t<li><code>1 <= matchsticks[i] <= 10<sup>8</sup></code></li>\n</ul>\n",
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"hints": [
"Treat the matchsticks as an array. Can we split the array into 4 equal halves?",
"Every matchstick can belong to either of the 4 sides. We don't know which one. Maybe try out all options!",
"For every matchstick, we have to try out each of the 4 options i.e. which side it can belong to. We can make use of recursion for this.",
"We don't really need to keep track of which matchsticks belong to a particular side during recursion. We just need to keep track of the <b>length</b> of each of the 4 sides.",
"When all matchsticks have been used we simply need to see the length of all 4 sides. If they're equal, we have a square on our hands!"
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