feat: 2025-10-23打卡

1138.alphabet-board-path.java

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+/*
+ * @lc app=leetcode id=1138 lang=java
+ *
+ * [1138] Alphabet Board Path
+ */
+
+// @lc code=start
+class Solution {
+    public String alphabetBoardPath(String target) {
+        char cur = 'a';
+        StringBuilder bd = new StringBuilder();
+        for(int i = 0; i < target.length(); i++) {
+            bd.append(actions(cur, target.charAt(i)));
+            cur = target.charAt(i);
+        }
+        return bd.toString();
+    }
+
+    private int[] distance(char a, char b) {
+        int[] pa = new int[] {
+            (a-'a') / 5,
+            (a-'a') % 5
+        };
+        int[] pb = new int[] {
+            (b - 'a') / 5,
+            (b - 'a') % 5
+        };
+        return new int[] {
+            pb[0] - pa[0],
+            pb[1] - pa[1]
+        };
+    }
+
+    private String actions(char s, char d) {
+        int[] move = distance(s, d);
+        StringBuilder builder = new StringBuilder();
+        if(move[0] == 0 && move[1] == 0) {
+            builder.append('!');
+        } else {
+            if(s == 'z') {
+                builder.append(rowActions(move[0]));
+                builder.append(colActions(move[1]));
+            } else {
+                builder.append(colActions(move[1]));
+                builder.append(rowActions(move[0]));
+            } 
+            builder.append('!');
+        }
+        return builder.toString();
+    }
+
+    private String rowActions(int x) {
+        if(x == 0) {
+            return "";
+        }
+        return x > 0 ? repeatChar('D', x):repeatChar('U', -x);
+    }
+
+    private String colActions(int x) {
+        if(x == 0) {
+            return "";
+        }
+        return x > 0 ? repeatChar('R', x):repeatChar('L', -x);
+    }
+
+    private String repeatChar(char ch, int n) {
+        StringBuilder s = new StringBuilder();
+        for(int i = 0; i<n; i++) {
+            s.append(ch);
+        }
+        return s.toString();
+    }
+}
+// @lc code=end
+