add: 自由之路

Author: yi-ge

README.md

@@ -661,6 +661,10 @@ Rust标准库`std::collections`提供了4种通用容器类型，包含一下8
 
 ### 其它
 
+- [自由之路](src/search/freedom_trail.rs)  [深度优先搜索, 广度优先搜索, 字符串, 动态规划]
+
+  - LeetCode 514. 自由之路 <https://leetcode.cn/problems/freedom-trail>
+
 - [赎金信](src/map/ransom_note.rs)  [哈希表, 字符串, 计数]
 
   - LeetCode 383. 赎金信 <https://leetcode.cn/problems/ransom-note>

images/search/freedom_trail.jpeg

@@ -0,0 +1,40 @@
+// 自由之路
+// https://leetcode.cn/problems/freedom-trail
+// INLINE  ../../images/search/freedom_trail.jpeg
+
+pub struct Solution;
+
+impl Solution {
+    pub fn find_rotate_steps(ring: String, key: String) -> i32 {
+        let mut idx_list: Vec<Vec<usize>> = vec![vec![]; 26];
+        let n = ring.len();
+        let m = key.len();
+        let mut pc = (ring.chars().next().unwrap() as u8 - b'a') as usize;
+
+        for (i, c) in ring.chars().enumerate() {
+            idx_list[(c as u8 - b'a') as usize].push(i);
+        }
+
+        let mut dp: Vec<i32> = vec![0x3f3f3f3f; n];
+        let mut pre: Vec<i32> = vec![0x3f3f3f3f; n];
+        pre[0] = 0;
+
+        for i in 0..m {
+            for &idx in &idx_list[key.chars().nth(i).unwrap() as usize - 'a' as usize] {
+                for &pi in &idx_list[pc] {
+                    dp[idx] = dp[idx].min(
+                        pre[pi]
+                            + (pi as i32 - idx as i32)
+                                .abs()
+                                .min(n as i32 - (pi as i32 - idx as i32).abs()),
+                    );
+                }
+            }
+            pre = dp.clone();
+            dp = vec![0x3f3f3f3f; n];
+            pc = key.chars().nth(i).unwrap() as usize - 'a' as usize;
+        }
+
+        *pre.iter().min().unwrap() + key.len() as i32
+    }
+}

src/search/freedom_trail.rs

@@ -1,7 +1,8 @@
+pub mod climbing_stairs;
 pub mod flip_chess;
+pub mod freedom_trail;
 pub mod minimum_moves_to_move_a_box_to_their_target_location;
 pub mod number_of_closed_islands;
+pub mod path_with_minimum_effort;
 pub mod pond_sizes_lcci;
 pub mod shortest_path_in_binary_matrix;
-pub mod climbing_stairs;
-pub mod path_with_minimum_effort;

src/search/mod.rs

@@ -0,0 +1,23 @@
+use rust_practice::search::freedom_trail::Solution;
+
+#[test]
+fn find_rotate_steps_test() {
+    // 示例 1：
+    // 输入: ring = "godding", key = "gd"
+    // 输出: 4
+    // 解释:
+    //  对于 key 的第一个字符 'g'，已经在正确的位置, 我们只需要1步来拼写这个字符。
+    //  对于 key 的第二个字符 'd'，我们需要逆时针旋转 ring "godding" 2步使它变成 "ddinggo"。
+    //  当然, 我们还需要1步进行拼写。
+    //  因此最终的输出是 4。
+    let ring = "godding".to_string();
+    let key = "gd".to_string();
+    assert_eq!(Solution::find_rotate_steps(ring, key), 4);
+
+    // 示例 2:
+    // 输入: ring = "godding", key = "godding"
+    // 输出: 13
+    let ring = "godding".to_string();
+    let key = "godding".to_string();
+    assert_eq!(Solution::find_rotate_steps(ring, key), 13);
+}

tests/search/freedom_trail_test.rs

@@ -5,3 +5,4 @@ pub mod pond_sizes_lcci_test;
 pub mod shortest_path_in_binary_matrix_test;
 pub mod climbing_stairs_test;
 pub mod path_with_minimum_effort_test;
+pub mod freedom_trail_test;