2285. Maximum Total Importance of Roads: RETRY, credit: https://leetcode.com/problems/maximum-total-importance-of-roads/solutions/5380938/rust-32ms-555mb-one-liner-solution-by-ro-xpyj/

Author: tan-wei

src/solution/mod.rs

@@ -1731,3 +1731,4 @@ mod s2280_minimum_lines_to_represent_a_line_chart;
 mod s2281_sum_of_total_strength_of_wizards;
 mod s2283_check_if_number_has_equal_digit_count_and_digit_value;
 mod s2284_sender_with_largest_word_count;
+mod s2285_maximum_total_importance_of_roads;

src/solution/s2285_maximum_total_importance_of_roads.rs

@@ -0,0 +1,104 @@
+/**
+ * [2285] Maximum Total Importance of Roads
+ *
+ * You are given an integer n denoting the number of cities in a country. The cities are numbered from 0 to n - 1.
+ * You are also given a 2D integer array roads where roads[i] = [ai, bi] denotes that there exists a bidirectional road connecting cities ai and bi.
+ * You need to assign each city with an integer value from 1 to n, where each value can only be used once. The importance of a road is then defined as the sum of the values of the two cities it connects.
+ * Return the maximum total importance of all roads possible after assigning the values optimally.
+ *  
+ * Example 1:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2022/04/07/ex1drawio.png" style="width: 290px; height: 215px;" />
+ * Input: n = 5, roads = [[0,1],[1,2],[2,3],[0,2],[1,3],[2,4]]
+ * Output: 43
+ * Explanation: The figure above shows the country and the assigned values of [2,4,5,3,1].
+ * - The road (0,1) has an importance of 2 + 4 = 6.
+ * - The road (1,2) has an importance of 4 + 5 = 9.
+ * - The road (2,3) has an importance of 5 + 3 = 8.
+ * - The road (0,2) has an importance of 2 + 5 = 7.
+ * - The road (1,3) has an importance of 4 + 3 = 7.
+ * - The road (2,4) has an importance of 5 + 1 = 6.
+ * The total importance of all roads is 6 + 9 + 8 + 7 + 7 + 6 = 43.
+ * It can be shown that we cannot obtain a greater total importance than 43.
+ *
+ * Example 2:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2022/04/07/ex2drawio.png" style="width: 281px; height: 151px;" />
+ * Input: n = 5, roads = [[0,3],[2,4],[1,3]]
+ * Output: 20
+ * Explanation: The figure above shows the country and the assigned values of [4,3,2,5,1].
+ * - The road (0,3) has an importance of 4 + 5 = 9.
+ * - The road (2,4) has an importance of 2 + 1 = 3.
+ * - The road (1,3) has an importance of 3 + 5 = 8.
+ * The total importance of all roads is 9 + 3 + 8 = 20.
+ * It can be shown that we cannot obtain a greater total importance than 20.
+ *
+ *  
+ * Constraints:
+ *
+ * 	2 <= n <= 5 * 10^4
+ * 	1 <= roads.length <= 5 * 10^4
+ * 	roads[i].length == 2
+ * 	0 <= ai, bi <= n - 1
+ * 	ai != bi
+ * 	There are no duplicate roads.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/maximum-total-importance-of-roads/
+// discuss: https://leetcode.com/problems/maximum-total-importance-of-roads/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    // Credit: https://leetcode.com/problems/maximum-total-importance-of-roads/solutions/5380938/rust-32ms-555mb-one-liner-solution-by-ro-xpyj/
+    pub fn maximum_importance(n: i32, roads: Vec<Vec<i32>>) -> i64 {
+        roads
+            .into_iter()
+            .fold(vec![0; n as usize], |mut v, x| {
+                v[x[0] as usize] += 1;
+                v[x[1] as usize] += 1;
+                v
+            })
+            .into_iter()
+            .collect::<std::collections::BinaryHeap<i32>>()
+            .into_sorted_vec()
+            .into_iter()
+            .enumerate()
+            .map(|(i, x)| (i + 1) as i64 * x as i64)
+            .sum::<i64>()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2285_example_1() {
+        let n = 5;
+        let roads = vec![
+            vec![0, 1],
+            vec![1, 2],
+            vec![2, 3],
+            vec![0, 2],
+            vec![1, 3],
+            vec![2, 4],
+        ];
+
+        let result = 43;
+
+        assert_eq!(Solution::maximum_importance(n, roads), result);
+    }
+
+    #[test]
+    fn test_2285_example_2() {
+        let n = 5;
+        let roads = vec![vec![0, 3], vec![2, 4], vec![1, 3]];
+
+        let result = 20;
+
+        assert_eq!(Solution::maximum_importance(n, roads), result);
+    }
+}