leetcode-problemset/leetcode/originData/count-nice-pairs-in-an-array.json

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        "question": {
            "questionId": "1925",
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            "title": "Count Nice Pairs in an Array",
            "titleSlug": "count-nice-pairs-in-an-array",
            "content": "<p>You are given an array <code>nums</code> that consists of non-negative integers. Let us define <code>rev(x)</code> as the reverse of the non-negative integer <code>x</code>. For example, <code>rev(123) = 321</code>, and <code>rev(120) = 21</code>. A pair of indices <code>(i, j)</code> is <strong>nice</strong> if it satisfies all of the following conditions:</p>\n\n<ul>\n\t<li><code>0 &lt;= i &lt; j &lt; nums.length</code></li>\n\t<li><code>nums[i] + rev(nums[j]) == nums[j] + rev(nums[i])</code></li>\n</ul>\n\n<p>Return <em>the number of nice pairs of indices</em>. Since that number can be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>\n\n<p>&nbsp;</p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> nums = [42,11,1,97]\n<strong>Output:</strong> 2\n<strong>Explanation:</strong> The two pairs are:\n - (0,3) : 42 + rev(97) = 42 + 79 = 121, 97 + rev(42) = 97 + 24 = 121.\n - (1,2) : 11 + rev(1) = 11 + 1 = 12, 1 + rev(11) = 1 + 11 = 12.\n</pre>\n\n<p><strong>Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> nums = [13,10,35,24,76]\n<strong>Output:</strong> 4\n</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>\n\t<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>\n</ul>\n",
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            "exampleTestcases": "[42,11,1,97]\n[13,10,35,24,76]",
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                    "lang": "C++",
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                    "code": "class Solution {\npublic:\n    int countNicePairs(vector<int>& nums) {\n        \n    }\n};",
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                    "code": "class Solution {\n    public int countNicePairs(int[] nums) {\n        \n    }\n}",
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                    "lang": "Python",
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                    "code": "class Solution(object):\n    def countNicePairs(self, nums):\n        \"\"\"\n        :type nums: List[int]\n        :rtype: int\n        \"\"\"\n        ",
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                    "code": "class Solution:\n    def countNicePairs(self, nums: List[int]) -> int:\n        ",
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                    "code": "\n\nint countNicePairs(int* nums, int numsSize){\n\n}",
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                    "code": "public class Solution {\n    public int CountNicePairs(int[] nums) {\n        \n    }\n}",
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                {
                    "lang": "JavaScript",
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                    "code": "/**\n * @param {number[]} nums\n * @return {number}\n */\nvar countNicePairs = function(nums) {\n    \n};",
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                    "lang": "Ruby",
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                    "code": "# @param {Integer[]} nums\n# @return {Integer}\ndef count_nice_pairs(nums)\n    \nend",
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                    "lang": "Swift",
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                    "code": "class Solution {\n    func countNicePairs(_ nums: [Int]) -> Int {\n        \n    }\n}",
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                {
                    "lang": "Go",
                    "langSlug": "golang",
                    "code": "func countNicePairs(nums []int) int {\n    \n}",
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                    "lang": "Scala",
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                    "code": "object Solution {\n    def countNicePairs(nums: Array[Int]): Int = {\n        \n    }\n}",
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                    "lang": "Kotlin",
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                    "code": "class Solution {\n    fun countNicePairs(nums: IntArray): Int {\n        \n    }\n}",
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                {
                    "lang": "Rust",
                    "langSlug": "rust",
                    "code": "impl Solution {\n    pub fn count_nice_pairs(nums: Vec<i32>) -> i32 {\n        \n    }\n}",
                    "__typename": "CodeSnippetNode"
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                {
                    "lang": "PHP",
                    "langSlug": "php",
                    "code": "class Solution {\n\n    /**\n     * @param Integer[] $nums\n     * @return Integer\n     */\n    function countNicePairs($nums) {\n        \n    }\n}",
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                    "code": "function countNicePairs(nums: number[]): number {\n\n};",
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                    "lang": "Racket",
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                    "code": "(define/contract (count-nice-pairs nums)\n  (-> (listof exact-integer?) exact-integer?)\n\n  )",
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                    "lang": "Erlang",
                    "langSlug": "erlang",
                    "code": "-spec count_nice_pairs(Nums :: [integer()]) -> integer().\ncount_nice_pairs(Nums) ->\n  .",
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                    "lang": "Elixir",
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                    "code": "defmodule Solution do\n  @spec count_nice_pairs(nums :: [integer]) :: integer\n  def count_nice_pairs(nums) do\n\n  end\nend",
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            "hints": [
                "The condition can be rearranged to (nums[i] - rev(nums[i])) == (nums[j] - rev(nums[j])).",
                "Transform each nums[i] into (nums[i] - rev(nums[i])). Then, count the number of (i, j) pairs that have equal values.",
                "Keep a map storing the frequencies of values that you have seen so far. For each i, check if nums[i] is in the map. If it is, then add that count to the overall count. Then, increment the frequency of nums[i]."
            ],
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            "sampleTestCase": "[42,11,1,97]",
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