1306. 跳跃游戏 III

src/main.rs

@@ -1,57 +1,49 @@
 mod arr;
 
 struct Solution {}
-use std::collections::hash_map::Entry;
-use std::collections::{HashMap, VecDeque};
+use std::collections::VecDeque;
 
 impl Solution {
-    pub fn min_jumps(arr: Vec<i32>) -> i32 {
-        let mut mp = HashMap::new();
-        for i in 0..arr.len() {
-            mp.entry(arr[i])
-                .and_modify(|x: &mut Vec<usize>| x.push(i))
-                .or_insert(vec![i]);
+    pub fn can_reach(arr: Vec<i32>, start: i32) -> bool {
+        let start = start as usize;
+        if arr[start] == 0 {
+            return true;
         }
         let mut depth = vec![arr.len() as i32 + 1; arr.len()];
-        depth[arr.len() - 1] = 0;
+        depth[start] = 0;
         let mut queue = VecDeque::new();
         let mut inserted = vec![false; arr.len()];
-        inserted[arr.len() - 1] = true;
-        queue.push_back(arr.len() - 1);
+        inserted[start] = true;
+        queue.push_back(start);
         while let Some(x) = queue.pop_front() {
-            if x > 0 {
-                if !inserted[x - 1] {
-                    depth[x - 1] = depth[x] + 1;
-                    queue.push_back(x - 1);
-                    inserted[x - 1] = true;
-                }
-            }
-            if x + 1 < arr.len() {
-                if !inserted[x + 1] {
-                    depth[x + 1] = depth[x] + 1;
-                    queue.push_back(x + 1);
-                    inserted[x + 1] = true;
-                }
-            }
-            if let Entry::Occupied(arr) = mp.entry(arr[x]) {
-                for y in arr.get() {
-                    if !inserted[*y] {
-                        depth[*y] = depth[x] + 1;
-                        queue.push_back(*y);
-                        inserted[*y] = true;
+            let y = x + arr[x] as usize;
+            let mut func = |inserted: &mut Vec<bool>, y: usize| -> bool {
+                if !inserted[y] {
+                    depth[y] = depth[x] + 1;
+                    queue.push_back(y);
+                    (*inserted)[y] = true;
+                    if arr[y] == 0 {
+                        return true;
                     }
                 }
+                return false;
+            };
+            if y < arr.len() {
+                if func(&mut inserted, y) {
+                    return true;
+                }
             }
-            if inserted[0] {
-                return depth[0];
+            let y = x as i32 - arr[x];
+            if y >= 0 {
+                let y = y as usize;
+                if func(&mut inserted, y) {
+                    return true;
+                }
             }
         }
-        -1
+        false
     }
 }
 fn main() {
-    println!(
-        "{:?}",
-        Solution::min_jumps(vec![100, -23, -23, 404, 100, 23, 23, 23, 3, 404])
-    );
+    println!("{:?}", Solution::can_reach(vec![4, 2, 3, 0, 3, 1, 2], 5));
 }