1534. Count Good Triplets: AC

Author: tan-wei

src/solution/mod.rs

@@ -1156,3 +1156,4 @@ mod s1528_shuffle_string;
 mod s1529_minimum_suffix_flips;
 mod s1530_number_of_good_leaf_nodes_pairs;
 mod s1531_string_compression_ii;
+mod s1534_count_good_triplets;

src/solution/s1534_count_good_triplets.rs

@@ -0,0 +1,106 @@
+/**
+ * [1534] Count Good Triplets
+ *
+ * Given an array of integers arr, and three integers a, b and c. You need to find the number of good triplets.
+ *
+ * A triplet (arr[i], arr[j], arr[k]) is good if the following conditions are true:
+ *
+ *
+ * 	0 <= i < j < k < arr.length
+ * 	|arr[i] - arr[j]| <= a
+ * 	|arr[j] - arr[k]| <= b
+ * 	|arr[i] - arr[k]| <= c
+ *
+ *
+ * Where |x| denotes the absolute value of x.
+ *
+ * Return the number of good triplets.
+ *
+ *  
+ * Example 1:
+ *
+ *
+ * Input: arr = [3,0,1,1,9,7], a = 7, b = 2, c = 3
+ * Output: 4
+ * Explanation: There are 4 good triplets: [(3,0,1), (3,0,1), (3,1,1), (0,1,1)].
+ *
+ *
+ * Example 2:
+ *
+ *
+ * Input: arr = [1,1,2,2,3], a = 0, b = 0, c = 1
+ * Output: 0
+ * Explanation: No triplet satisfies all conditions.
+ *
+ *
+ *  
+ * Constraints:
+ *
+ *
+ * 	3 <= arr.length <= 100
+ * 	0 <= arr[i] <= 1000
+ * 	0 <= a, b, c <= 1000
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/count-good-triplets/
+// discuss: https://leetcode.com/problems/count-good-triplets/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_good_triplets(arr: Vec<i32>, a: i32, b: i32, c: i32) -> i32 {
+        let mut counter = 0;
+        let l = arr.len();
+
+        arr[..l - 2].iter().enumerate().for_each(|(i, &ai)| {
+            arr[..l - 1]
+                .iter()
+                .enumerate()
+                .skip(i + 1)
+                .filter(|(_, aj)| (ai - **aj).abs() <= a)
+                .for_each(|(j, &aj)| {
+                    arr[j + 1..l]
+                        .iter()
+                        .filter(|&&ak| (aj - ak).abs() <= b && (ai - ak).abs() <= c)
+                        .for_each(|_| {
+                            counter += 1;
+                        })
+                })
+        });
+
+        counter
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1534_example_1() {
+        let arr = vec![3, 0, 1, 1, 9, 7];
+        let a = 7;
+        let b = 2;
+        let c = 3;
+
+        let result = 4;
+
+        assert_eq!(Solution::count_good_triplets(arr, a, b, c), result);
+    }
+
+    #[test]
+    fn test_1534_example_2() {
+        let arr = vec![1, 1, 2, 2, 3];
+        let a = 0;
+        let b = 0;
+        let c = 1;
+
+        let result = 0;
+
+        assert_eq!(Solution::count_good_triplets(arr, a, b, c), result);
+    }
+}