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Author: NamVr

2095-minimum-number-of-swaps-to-make-the-string-balanced/README.md

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+<p>You are given a <strong>0-indexed</strong> string <code>s</code> of <strong>even</strong> length <code>n</code>. The string consists of <strong>exactly</strong> <code>n / 2</code> opening brackets <code>&#39;[&#39;</code> and <code>n / 2</code> closing brackets <code>&#39;]&#39;</code>.</p>
+
+<p>A string is called <strong>balanced</strong> if and only if:</p>
+
+<ul>
+	<li>It is the empty string, or</li>
+	<li>It can be written as <code>AB</code>, where both <code>A</code> and <code>B</code> are <strong>balanced</strong> strings, or</li>
+	<li>It can be written as <code>[C]</code>, where <code>C</code> is a <strong>balanced</strong> string.</li>
+</ul>
+
+<p>You may swap the brackets at <strong>any</strong> two indices <strong>any</strong> number of times.</p>
+
+<p>Return <em>the <strong>minimum</strong> number of swaps to make </em><code>s</code> <em><strong>balanced</strong></em>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;][][&quot;
+<strong>Output:</strong> 1
+<strong>Explanation:</strong> You can make the string balanced by swapping index 0 with index 3.
+The resulting string is &quot;[[]]&quot;.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;]]][[[&quot;
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> You can do the following to make the string balanced:
+- Swap index 0 with index 4. s = &quot;[]][][&quot;.
+- Swap index 1 with index 5. s = &quot;[[][]]&quot;.
+The resulting string is &quot;[[][]]&quot;.
+</pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;[]&quot;
+<strong>Output:</strong> 0
+<strong>Explanation:</strong> The string is already balanced.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>n == s.length</code></li>
+	<li><code>2 &lt;= n &lt;= 10<sup>6</sup></code></li>
+	<li><code>n</code> is even.</li>
+	<li><code>s[i]</code> is either <code>&#39;[&#39; </code>or <code>&#39;]&#39;</code>.</li>
+	<li>The number of opening brackets <code>&#39;[&#39;</code> equals <code>n / 2</code>, and the number of closing brackets <code>&#39;]&#39;</code> equals <code>n / 2</code>.</li>
+</ul>

2095-minimum-number-of-swaps-to-make-the-string-balanced/solution.cpp

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+class Solution {
+public:
+    int minSwaps(string s) {
+        int x = 0;
+
+        for (char c : s) {
+            if (c == '[') x++;
+            else if (x > 0) x--;
+        }
+
+        return (x+1)/2;
+    }
+};