"content":"<p>Given a string <code>s</code> and an integer <code>k</code>, partition <code>s</code> into <code>k</code> <strong>substrings</strong> such that the sum of the number of letter changes required to turn each <strong>substring</strong> into a <strong>semi-palindrome</strong> is minimized.</p>\n\n<p>Return <em>an integer denoting the <strong>minimum</strong> number of letter changes required.</em></p>\n\n<p><strong>Notes</strong></p>\n\n<ul>\n\t<li>A string is a <strong>palindrome</strong> if it can be read the same way from left to right and right to left.</li>\n\t<li>A string with a length of <code>len</code> is considered a <strong>semi-palindrome</strong> if there exists a positive integer <code>d</code> such that <code>1 <= d < len</code> and <code>len % d == 0</code>, and if we take indices that have the same modulo by <code>d</code>, they form a <strong>palindrome</strong>. For example, <code>"aa"</code>, <code>"aba"</code>, <code>"adbgad"</code>, and, <code>"abab"</code> are <strong>semi-palindrome</strong> and <code>"a"</code>, <code>"ab"</code>, and, <code>"abca"</code> are not.</li>\n\t<li>A <strong>substring</strong> is a contiguous sequence of characters within a string.</li>\n</ul>\n\n<p> </p>\n<p><strong class=\"example\">Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> s = "abcac", k = 2\n<strong>Output:</strong> 1\n<strong>Explanation:</strong> We can divide s into substrings "ab" and "cac". The string "cac" is already a semi-palindrome. If we change "ab" to "aa", it becomes a semi-palindrome with d = 1.\nIt can be shown that there is no way to divide the string "abcac" into two semi-palindrome substrings. Therefore, the answer would be at least 1.</pre>\n\n<p><strong class=\"example\">Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> s = "abcdef", k = 2\n<strong>Output:</strong> 2\n<strong>Explanation:</strong> We can divide it into substrings "abc" and "def". Each of the substrings "abc" and "def" requires one change to become a semi-palindrome, so we need 2 changes in total to make all substrings semi-palindrome.\nIt can be shown that we cannot divide the given string into two substrings in a way that it would require less than 2 changes.</pre>\n\n<p><strong class=\"example\">Example 3:</strong></p>\n\n<pre>\n<strong>Input:</strong> s = "aabbaa", k = 3\n<strong>Output:</strong> 0\n<strong>Explanation:</strong> We can divide it into substrings "aa", "bb" and "aa".\nThe strings "aa" and "bb" are already semi-palindromes. Thus, the answer is zero.\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>2 <= s.length <= 200</code></li>\n\t<li><code>1 <= k <= s.length / 2</code></li>\n\t<li><code>s</code> consists only of lowercase English letters.</li>\n</ul>\n",
"Define <code>dp[i][j]</code> as the minimum count of letter changes needed to split the suffix of string <code>s</code> starting from <code>s[i]</code> into <code>j</code> valid parts.",
"We have <code>dp[i][j] = min(dp[x + 1][j - 1] + v[i][x])</code>. Here <code>v[i][x]</code> is the minimum number of letter changes to change substring <code>s[i..x]</code> into semi-palindrome.",
"<code>v[i][j]</code> can be calculated separately by <b>brute-force</b>. We can create a table of <code>v[i][j]</code> independently to improve the complexity. Also note that semi-palindrome’s length is at least <code>2</code>."
"envInfo":"{\"cpp\": [\"C++\", \"<p>Compiled with <code> clang 11 </code> using the latest C++ 20 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level two optimization (<code>-O2</code>). <a href=\\\"https://github.com/google/sanitizers/wiki/AddressSanitizer\\\" target=\\\"_blank\\\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\"], \"java\": [\"Java\", \"<p><code>OpenJDK 17</code>. Java 8 features such as lambda expressions and stream API can be used. </p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\\r\\n<p>Includes <code>Pair</code> class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.</p>\"], \"python\": [\"Python\", \"<p><code>Python 2.7.12</code>.</p>\\r\\n\\r\\n<p>Most libraries are already imported automatically for your convenience, such as <a href=\\\"https://docs.python.org/2/library/array.html\\\" target=\\\"_blank\\\">array</a>, <a href=\\\"https://docs.python.org/2/library/bisect.html\\\" target=\\\"_blank\\\">bisect</a>, <a href=\\\"https://docs.python.org/2/library/collections.html\\\" target=\\\"_blank\\\">collections</a>. If you need more libraries, you can import it yourself.</p>\\r\\n\\r\\n<p>For Map/TreeMap data structure, you may use <a href=\\\"http://www.grantjenks.com/docs/sortedcontainers/\\\" target=\\\"_blank\\\">sortedcontainers</a> library.</p>\\r\\n\\r\\n<p>Note that Python 2.7 <a href=\\\"https://www.python.org/dev/peps/pep-0373/\\\" target=\\\"_blank\\\">will not be maintained past 2020</a>. For the latest Python, please choose Python3 instead.</p>\"], \"c\": [\"C\", \"<p>Compiled with <code>gcc 8.2</code> using the gnu11 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level one optimization (<code>-O1</code>). <a href=\\\"https://github.com/google/sanitizers/wiki/AddressSanitizer\\\" target=\\\"_blank\\\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\\r\\n\\r\\n<p>For hash table operations, you may use <a href=\\\"https://troydhanson.github.io/uthash/\\\" target=\\\"_blank\\\">uthash</a>. \\\"uthash.h\\\" is included by default. Below are some examples:</p>\\r\\n\\r\\n<p><b>1. Adding an item to a hash.</b>\\r\\n<pre>\\r\\nstruct hash_entry {\\r\\n int id; /* we'll use this field as the key */\\r\\n char name[10];\\r\\n UT_hash_handle hh; /* makes this structure hashable */\\r\\n};\\r\\n\\r\\nstruct hash_entry *users = NULL;\\r\\n\\r\\nvoid add_user(struct hash_entry *s) {\\r\\n HASH_ADD_INT(users, id, s);\\r\\n}\\r\\n</pre>\\r\\n</p>\\r\\n\\r\\n<p><b>2. Looking up an item in a hash:</b>\\r\\n<pre>\\r\\nstruct hash_entry *find_user(int user_id) {\\r\\n struct hash_entry *s;\\r\\n HASH_FIND_INT(users, &user_id, s);\\r\\n return s;\\r\\n}\\r\\n</pre>\\r\\n</p>\\r\\n\\r\\n<p><b>3. Deleting an item in a hash:</b>\\r\\n<pre>\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n HASH_DEL(users, user); \\r\\n}\\r\\n</pre>\\r\\n</p>\"], \"csharp\": [\"C#\", \"<p><a href=\\\"https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-10\\\" target=\\\"_blank\\\">C# 10 with .NET 6 runtime</a></p>\"], \"javascript\": [\"JavaScript\", \"<p><code>Node.js 16.13.2</code>.</p>\\r\\n\\r\\n<p>Your code is run with <code>--harmony</code> flag, enabling <a href=\\\"http://node.green/\\\" target=\\\"_blank\\\">new ES6 features</a>.</p>\\r\\n\\r\\n<p><a href=\\\"https://lodash.com\\\" target=\\\"_blank\\\">lodash.js</a> library is included by default.</p>\\r\\n\\r\\n<p>For Priority Queue / Queue data structures, you may use 5.3.0 version of <a href=\\\"https://github.com/datastructures-js/priority-queue/tree/fb4fdb984834421279aeb081df7af624d17c2a03\\\" target=\\\"_blank\\\">datastructures-js/priority-queue</a> and 4.2.1 version of <a href=\\\"https://githu
