[LEET-153] add 153

Author: fishercoder1534

leetcode-algorithms/README.md

@@ -234,6 +234,7 @@
 |157|[Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/ReadNCharactersGivenRead4.java)| O(n)|O(1) | Easy| 
 |156|[Binary Tree Upside Down](https://leetcode.com/problems/binary-tree-upside-down/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/BinaryTreeUpsideDown.java)| O(n)|O(h) | Medium| Tree, Recursion
 |155|[Min Stack](https://leetcode.com/problems/min-stack/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/MinStack.java)| O(1)|O(n) | Easy| Stack
+|153|[Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/FindMinimuminRotatedSortedArray.java)| O(logn)|O(1) | Medium| Array, Binary Search
 |152|[Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/MaximumProductSubarray.java)| O(n)|O(1) | Medium| Array
 |151|[Reverse Words in a String](https://leetcode.com/problems/reverse-words-in-a-string/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/ReverseWordsinaString.java)| O(n)|O(n) | Medium|
 |150|[Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/EvaluateReversePolishNotation.java)| O(?)|O(?) | Medium

leetcode-algorithms/src/main/java/com/stevesun/solutions/FindMinimuminRotatedSortedArray.java

@@ -0,0 +1,34 @@
+package com.stevesun.solutions;
+
+/**
+ * Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
+
+ (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).
+
+ Find the minimum element.
+
+ You may assume no duplicate exists in the array.
+ */
+public class FindMinimuminRotatedSortedArray {
+
+    public int findMin(int[] nums) {
+        int left = 0;
+        int right = nums.length-1;
+        if (nums[left] < nums[right]) return nums[left];
+        int min = nums[0];
+        while (left + 1 < right) {
+            int mid = left + (right-left)/2;
+            min = Math.min(min, nums[mid]);
+            if (nums[mid] > nums[left]) {
+                min = Math.min(nums[left], min);
+                left = mid+1;
+            }
+            else if (nums[mid] < nums[left]) {
+                right = mid-1;
+            }
+        }
+        min = Math.min(min, Math.min(nums[left], nums[right]));
+        return min;
+    }
+
+}

leetcode-algorithms/src/test/java/com/stevesun/FindMinimuminRotatedSortedArrayTest.java

@@ -0,0 +1,60 @@
+package com.stevesun;
+
+import com.stevesun.solutions.FindMinimuminRotatedSortedArray;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by stevesun on 1/10/17.
+ */
+public class FindMinimuminRotatedSortedArrayTest {
+    private static FindMinimuminRotatedSortedArray test;
+    private static int expected;
+    private static int actual;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup(){
+        test = new FindMinimuminRotatedSortedArray();
+    }
+
+    @Before
+    public void setupForEachTest(){}
+
+    @Test
+    public void test1(){
+
+        nums = new int[]{4, 5, 6, 7, 0, 1, 2};
+        expected = 0;
+        actual = test.findMin(nums);
+        assertEquals(expected, actual);
+
+    }
+
+    @Test
+    public void test2(){
+        nums = new int[]{1};
+        expected = 1;
+        actual = test.findMin(nums);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void test3(){
+        nums = new int[]{2, 1};
+        expected = 1;
+        actual = test.findMin(nums);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void test4(){
+        nums = new int[]{2,3,4,5,1};
+        expected = 1;
+        actual = test.findMin(nums);
+        assertEquals(expected, actual);
+    }
+}