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rust/2642-design-graph-with-shortest-path-calculator.rs

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+#![allow(dead_code)]
+
+/*
+ * @lc app=leetcode id=2642 lang=rust
+ *
+ * [2642] Design Graph With Shortest Path Calculator
+ */
+
+// @lc code=start
+
+use std::{collections::BinaryHeap, fmt::Display};
+
+struct GraphNode {
+    id: usize,
+    cost: usize,
+}
+
+impl From<&Vec<i32>> for GraphNode {
+    fn from(edge: &Vec<i32>) -> Self {
+        Self {
+            id: check_positive(edge[1]).unwrap(),
+            cost: check_positive(edge[2]).unwrap()
+        }
+    }
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+struct State {
+    cost: usize,
+    position: usize,
+}
+
+impl Ord for State {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        other
+            .cost
+            .cmp(&self.cost)
+            .then_with(|| self.position.cmp(&other.position))
+    }
+}
+impl PartialOrd for State {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+struct Graph {
+    graph: Vec<Vec<GraphNode>>,
+}
+#[derive(Debug, Clone)]
+struct NegativeError;
+
+impl Display for NegativeError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "input value was negative")
+    }
+}
+
+fn check_positive(a: i32) -> Result<usize, NegativeError> {
+    if a < 0 {
+        return Err(NegativeError)
+    } else {
+        Ok(a as usize)
+    }
+}
+
+impl Graph {
+    fn new(n: i32, edges: Vec<Vec<i32>>) -> Self {
+        let n = check_positive(n).unwrap(); 
+        // Vec with n items, graph[node_int] = [Edge neighbors {node: other_int, cost: #}]
+        let mut graph: Vec<Vec<GraphNode>> = Vec::with_capacity(n as usize);
+        for _ in 0..n {
+            graph.push(Vec::new());
+        }
+        for edge in edges.iter() {
+            match edge.len() {
+                3 => {
+                    graph[edge[0] as usize].push(GraphNode::from(edge));
+                }
+                _ => panic!(
+                    "Invalid input format, edge must have format [to, from, cost] {:?}",
+                    edge
+                ),
+            }
+        }
+        Self { graph }
+    }
+
+    fn add_edge(&mut self, edge: Vec<i32>) {
+        // Create new Edge, addd to graph[edge[0]]
+        match edge.len() {
+            3 => {
+                let node = GraphNode::from(&edge);
+                self.graph[edge[0] as usize].push(node);
+            }
+            _ => panic!(
+                "Invalid input format, edge must have format [to, from, cost] {:?}",
+                edge
+            ),
+        }
+    }
+
+    fn shortest_path(&mut self, node1: i32, node2: i32) -> i32 {
+        let start = check_positive(node1).unwrap();
+        let end = check_positive(node2).unwrap();
+        let mut dist: Vec<usize> = vec![usize::MAX; self.graph.len()];
+        let mut heap = BinaryHeap::new();
+
+        dist[start] = 0;
+        heap.push(State {
+            cost: 0,
+            position: start
+        });
+        while let Some(State { cost, position }) = heap.pop() {
+            if position == end {
+                return cost as i32;
+            }
+            if cost > dist[position] {
+                continue;
+            }
+            for edge in &self.graph[position] {
+                let next = State {cost: cost + edge.cost, position: edge.id as usize};
+                if next.cost < dist[next.position] {
+                    heap.push(next);
+                    dist[next.position] = next.cost;
+                }
+            }
+        }
+        -1
+    }
+}
+
+// @lc code=end
+fn main() {
+    unimplemented!();
+}