1577. Number of Ways Where Square of Number Is Equal to Product of Two Numbers: AC

Author: tan-wei

src/solution/mod.rs

@@ -1189,3 +1189,4 @@ mod s1573_number_of_ways_to_split_a_string;
 mod s1574_shortest_subarray_to_be_removed_to_make_array_sorted;
 mod s1575_count_all_possible_routes;
 mod s1576_replace_all_s_to_avoid_consecutive_repeating_characters;
+mod s1577_number_of_ways_where_square_of_number_is_equal_to_product_of_two_numbers;

src/solution/s1577_number_of_ways_where_square_of_number_is_equal_to_product_of_two_numbers.rs

@@ -0,0 +1,120 @@
+/**
+ * [1577] Number of Ways Where Square of Number Is Equal to Product of Two Numbers
+ *
+ * Given two arrays of integers nums1 and nums2, return the number of triplets formed (type 1 and type 2) under the following rules:
+ *
+ * 	Type 1: Triplet (i, j, k) if nums1[i]^2 == nums2[j] * nums2[k] where 0 <= i < nums1.length and 0 <= j < k < nums2.length.
+ * 	Type 2: Triplet (i, j, k) if nums2[i]^2 == nums1[j] * nums1[k] where 0 <= i < nums2.length and 0 <= j < k < nums1.length.
+ *
+ *  
+ * Example 1:
+ *
+ * Input: nums1 = [7,4], nums2 = [5,2,8,9]
+ * Output: 1
+ * Explanation: Type 1: (1, 1, 2), nums1[1]^2 = nums2[1] * nums2[2]. (4^2 = 2 * 8).
+ *
+ * Example 2:
+ *
+ * Input: nums1 = [1,1], nums2 = [1,1,1]
+ * Output: 9
+ * Explanation: All Triplets are valid, because 1^2 = 1 * 1.
+ * Type 1: (0,0,1), (0,0,2), (0,1,2), (1,0,1), (1,0,2), (1,1,2).  nums1[i]^2 = nums2[j] * nums2[k].
+ * Type 2: (0,0,1), (1,0,1), (2,0,1). nums2[i]^2 = nums1[j] * nums1[k].
+ *
+ * Example 3:
+ *
+ * Input: nums1 = [7,7,8,3], nums2 = [1,2,9,7]
+ * Output: 2
+ * Explanation: There are 2 valid triplets.
+ * Type 1: (3,0,2).  nums1[3]^2 = nums2[0] * nums2[2].
+ * Type 2: (3,0,1).  nums2[3]^2 = nums1[0] * nums1[1].
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= nums1.length, nums2.length <= 1000
+ * 	1 <= nums1[i], nums2[i] <= 10^5
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/
+// discuss: https://leetcode.com/problems/number-of-ways-where-square-of-number-is-equal-to-product-of-two-numbers/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn num_triplets(nums1: Vec<i32>, nums2: Vec<i32>) -> i32 {
+        let mut result = 0;
+
+        let (mut m1, mut m2) = (
+            std::collections::HashMap::new(),
+            std::collections::HashMap::new(),
+        );
+
+        for i in 0..nums1.len() {
+            for j in i + 1..nums1.len() {
+                let p = nums1[i] as i64 * nums1[j] as i64;
+                *m1.entry(p).or_insert(0) += 1;
+            }
+        }
+
+        for i in 0..nums2.len() {
+            for j in i + 1..nums2.len() {
+                let p = nums2[i] as i64 * nums2[j] as i64;
+                *m2.entry(p).or_insert(0) += 1;
+            }
+        }
+
+        for &num in nums1.iter() {
+            if let Some(&v) = m2.get(&(num as i64 * num as i64)) {
+                result += v;
+            }
+        }
+
+        for &num in nums2.iter() {
+            if let Some(&v) = m1.get(&(num as i64 * num as i64)) {
+                result += v;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1577_example_1() {
+        let nums1 = vec![7, 4];
+        let nums2 = vec![5, 2, 8, 9];
+
+        let result = 1;
+
+        assert_eq!(Solution::num_triplets(nums1, nums2), result);
+    }
+
+    #[test]
+    fn test_1577_example_2() {
+        let nums1 = vec![1, 1];
+        let nums2 = vec![1, 1, 1];
+
+        let result = 9;
+
+        assert_eq!(Solution::num_triplets(nums1, nums2), result);
+    }
+
+    #[test]
+    fn test_1577_example_3() {
+        let nums1 = vec![7, 7, 8, 3];
+        let nums2 = vec![1, 2, 9, 7];
+
+        let result = 2;
+
+        assert_eq!(Solution::num_triplets(nums1, nums2), result);
+    }
+}