Create 24-frog-position-after-t-seconds.rs

2023/05/24-frog-position-after-t-seconds.rs

@@ -0,0 +1,50 @@
+// https://leetcode.cn/problems/frog-position-after-t-seconds/
+
+impl Solution {
+    pub fn frog_position(n: i32, edges: Vec<Vec<i32>>, t: i32, target: i32) -> f64 {
+        let mut g = vec![vec![]; n as usize + 1];
+        for edge in edges {
+            g[edge[0] as usize].push(edge[1] as usize);
+            g[edge[1] as usize].push(edge[0] as usize);
+        }
+        let mut vis = vec![false; n as usize + 1];
+        vis[1] = true;
+        fn dfs(
+            edges: &Vec<Vec<usize>>,
+            pos: usize,
+            probability: f64,
+            vis: &mut Vec<bool>,
+            t: i32,
+            target: i32,
+        ) -> f64 {
+            if t == 0 {
+                if pos as i32 == target {
+                    return probability;
+                } else {
+                    return 0.0;
+                }
+            }
+            let cnt = edges[pos]
+                .iter()
+                .filter(|&x| !vis[*x])
+                .count();
+            if cnt == 0 {
+                if pos as i32 == target {
+                    return probability;
+                } else {
+                    return 0.0;
+                }
+            }
+            let mut ans = 0.0;
+            for &next in edges[pos].iter() {
+                if !vis[next] {
+                    vis[next] = true;
+                    ans += dfs(edges, next, probability / cnt as f64, vis, t - 1, target);
+                    vis[next] = false;
+                }
+            }
+            ans
+        }
+        dfs(&g, 1, 1.0, &mut vis, t, target)
+    }
+}