189.Rotate

Author: YimingWei

Rotate.java

@@ -0,0 +1,19 @@
+class Solution {
+    private void reverse(int[] nums, int start, int end) {
+        while (start < end) {
+        int temp = nums[start];
+        nums[start] = nums[end];
+        nums[end] = temp;
+        start++;
+        end--;
+        }
+    }
+
+    public void rotate(int[] nums, int k) {
+        int n = nums.length;
+        k %= n; //一定要取余，避免indexOfRange错误
+        reverse(nums, 0, n-1); //先整体翻转
+        reverse(nums, 0, k-1); //再翻转第 1 到 k 个数
+        reverse(nums, k, n-1); //最后翻转第 k+1 到第 n 个数
+    }
+}