日常水题

Author: programmerhjh

src/myleetcode/PalindromeNumber.java

@@ -0,0 +1,76 @@
+package myleetcode;
+
+/**
+ * 回文数
+ * @author acer
+ *
+ */
+public class PalindromeNumber {
+
+	public static void main(String[] args) {
+		System.out.println(isPalindrome(-121));
+	}
+	
+	public static boolean isPalindrome(int x) {
+		boolean result = true;
+		if (x < 0) {
+			result = false;
+			return result;
+		}
+		int times = 1;
+		int x1 = x;
+		while(x1 / 10 != 0) {
+			x1 = x1 / 10;
+			times ++;
+		}
+		if (times <= 1) {
+			return result;
+		} else if (times == 2 && x % 11 == 0) {
+			return result;
+		}
+		boolean flag = true;
+		int i = 1;
+		int mid = times / 2;
+		if (times % 2 == 0) {
+			while (flag) {
+				int left = (x / (int)Math.pow(10, mid+i-1)) % 10;
+				int powRight = (int)Math.pow(10, mid-i+1);
+				int right = x % powRight;
+				if (right >= powRight/10) {
+					right = right / (powRight / 10);
+				} else {
+					right = 0;
+				}
+				if (left != right) {
+					result = false;
+					break;
+				}
+				if (i + mid == times - 1) {
+					flag = false;
+				}
+				i ++;
+			}
+		} else {
+			while (flag) {
+				int left = (x / (int)Math.pow(10, mid+i)) % 10;
+				int powRight = (int)Math.pow(10, mid-i+1);
+				int right = x % powRight;
+				if (right >= powRight / 10) {
+					right = right / (powRight / 10);
+				} else {
+					right = 0;
+				}
+				if (left != right) {
+					result = false;
+					break;
+				}
+				if (i + mid == times - 1) {
+					flag = false;
+				}
+				i ++;
+			}
+		}
+		return result;
+    }
+	
+}