2161. Partition Array According to Given Pivot: AC

Author: tan-wei

src/solution/mod.rs

@@ -1632,3 +1632,4 @@ mod s2155_all_divisions_with_the_highest_score_of_a_binary_array;
 mod s2156_find_substring_with_given_hash_value;
 mod s2157_groups_of_strings;
 mod s2160_minimum_sum_of_four_digit_number_after_splitting_digits;
+mod s2161_partition_array_according_to_given_pivot;

src/solution/s2161_partition_array_according_to_given_pivot.rs

@@ -0,0 +1,86 @@
+/**
+ * [2161] Partition Array According to Given Pivot
+ *
+ * You are given a 0-indexed integer array nums and an integer pivot. Rearrange nums such that the following conditions are satisfied:
+ *
+ * 	Every element less than pivot appears before every element greater than pivot.
+ * 	Every element equal to pivot appears in between the elements less than and greater than pivot.
+ * 	The relative order of the elements less than pivot and the elements greater than pivot is maintained.
+ *
+ * 		More formally, consider every pi, pj where pi is the new position of the i^th element and pj is the new position of the j^th element. If i < j and both elements are smaller (or larger) than pivot, then pi < pj.
+ *
+ *
+ *
+ * Return nums after the rearrangement.
+ *  
+ * Example 1:
+ *
+ * Input: nums = [9,12,5,10,14,3,10], pivot = 10
+ * Output: [9,5,3,10,10,12,14]
+ * Explanation:
+ * The elements 9, 5, and 3 are less than the pivot so they are on the left side of the array.
+ * The elements 12 and 14 are greater than the pivot so they are on the right side of the array.
+ * The relative ordering of the elements less than and greater than pivot is also maintained. [9, 5, 3] and [12, 14] are the respective orderings.
+ *
+ * Example 2:
+ *
+ * Input: nums = [-3,4,3,2], pivot = 2
+ * Output: [-3,2,4,3]
+ * Explanation:
+ * The element -3 is less than the pivot so it is on the left side of the array.
+ * The elements 4 and 3 are greater than the pivot so they are on the right side of the array.
+ * The relative ordering of the elements less than and greater than pivot is also maintained. [-3] and [4, 3] are the respective orderings.
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= nums.length <= 10^5
+ * 	-10^6 <= nums[i] <= 10^6
+ * 	pivot equals to an element of nums.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/partition-array-according-to-given-pivot/
+// discuss: https://leetcode.com/problems/partition-array-according-to-given-pivot/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn pivot_array(nums: Vec<i32>, pivot: i32) -> Vec<i32> {
+        let (mut less, mut equal, mut greater) = (Vec::new(), Vec::new(), Vec::new());
+        nums.into_iter().for_each(|num| match num.cmp(&pivot) {
+            std::cmp::Ordering::Less => less.push(num),
+            std::cmp::Ordering::Equal => equal.push(num),
+            std::cmp::Ordering::Greater => greater.push(num),
+        });
+        [less, equal, greater].concat()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2161_example_1() {
+        let nums = vec![9, 12, 5, 10, 14, 3, 10];
+        let pivot = 10;
+
+        let result = vec![9, 5, 3, 10, 10, 12, 14];
+
+        assert_eq!(Solution::pivot_array(nums, pivot), result);
+    }
+
+    #[test]
+    fn test_2161_example_2() {
+        let nums = vec![-3, 4, 3, 2];
+        let pivot = 2;
+
+        let result = vec![-3, 2, 4, 3];
+
+        assert_eq!(Solution::pivot_array(nums, pivot), result);
+    }
+}