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"content": "<p>You are given two strings <code>s</code> and <code>t</code> of equal length <code>n</code>. You can perform the following operation on the string <code>s</code>:</p>\n\n<ul>\n\t<li>Remove a <strong>suffix</strong> of <code>s</code> of length <code>l</code> where <code>0 < l < n</code> and append it at the start of <code>s</code>.<br />\n\tFor example, let <code>s = 'abcd'</code> then in one operation you can remove the suffix <code>'cd'</code> and append it in front of <code>s</code> making <code>s = 'cdab'</code>.</li>\n</ul>\n\n<p>You are also given an integer <code>k</code>. Return <em>the number of ways in which </em><code>s</code> <em>can be transformed into </em><code>t</code><em> in <strong>exactly</strong> </em><code>k</code><em> operations.</em></p>\n\n<p>Since the answer can be large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>\n\n<p> </p>\n<p><strong class=\"example\">Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> s = "abcd", t = "cdab", k = 2\n<strong>Output:</strong> 2\n<strong>Explanation:</strong> \nFirst way:\nIn first operation, choose suffix from index = 3, so resulting s = "dabc".\nIn second operation, choose suffix from index = 3, so resulting s = "cdab".\n\nSecond way:\nIn first operation, choose suffix from index = 1, so resulting s = "bcda".\nIn second operation, choose suffix from index = 1, so resulting s = "cdab".\n</pre>\n\n<p><strong class=\"example\">Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> s = "ababab", t = "ababab", k = 1\n<strong>Output:</strong> 2\n<strong>Explanation:</strong> \nFirst way:\nChoose suffix from index = 2, so resulting s = "ababab".\n\nSecond way:\nChoose suffix from index = 4, so resulting s = "ababab".\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>2 <= s.length <= 5 * 10<sup>5</sup></code></li>\n\t<li><code>1 <= k <= 10<sup>15</sup></code></li>\n\t<li><code>s.length == t.length</code></li>\n\t<li><code>s</code> and <code>t</code> consist of only lowercase English alphabets.</li>\n</ul>\n",
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"code": "class Solution(object):\n def numberOfWays(self, s, t, k):\n \"\"\"\n :type s: str\n :type t: str\n :type k: int\n :rtype: int\n \"\"\"\n ",
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"code": "/**\n * @param {string} s\n * @param {string} t\n * @param {number} k\n * @return {number}\n */\nvar numberOfWays = function(s, t, k) {\n \n};",
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"code": "# @param {String} s\n# @param {String} t\n# @param {Integer} k\n# @return {Integer}\ndef number_of_ways(s, t, k)\n \nend",
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"code": "defmodule Solution do\n @spec number_of_ways(s :: String.t, t :: String.t, k :: integer) :: integer\n def number_of_ways(s, t, k) do\n\n end\nend",
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"hints": [
"String <code>t</code> can be only constructed if it is a rotated version of string <code>s</code>.",
"Use KMP algorithm or Z algorithm to find the number of indices from where <code>s</code> is equal to <code>t</code>.",
"Use Dynamic Programming to count the number of ways."
],
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