feat: 2025-10-28打卡

50.pow-x-n.java

@@ -0,0 +1,33 @@
+/*
+ * @lc app=leetcode id=50 lang=java
+ *
+ * [50] Pow(x, n)
+ */
+
+// @lc code=start
+
+import java.util.Map;
+
+class Solution {
+    public double myPow(double x, int n) {
+        Map<Long, Double> track = new HashMap<>();
+        long m = n;
+        return m>=0?myPow(x, m, track):1/myPow(x, -m, track);
+    }
+
+    private double myPow(double x, long n, Map<Long, Double> track) {
+        if(n < 0) {
+            throw new RuntimeException("not supported number");
+        } else if(n <= 1) {
+            return n==0?1:x;
+        } else if(track.containsKey(n)) {
+            return track.get(n);
+        }
+        long l = n / 2;
+        double r = myPow(x, l, track) * myPow(x, n-l, track);
+        track.put(n, r);
+        return r;
+    }
+}
+// @lc code=end
+