java: add problem 4 and unit test

Author: supercoderhawk

Java/src/main/java/com/supercoderhawk/Solution_1_10.java

@@ -3,12 +3,69 @@
 public class Solution_1_10 {
   /**
    * problem 1
-   * @param nums: 输入数组
+   *
+   * @param nums:   输入数组
    * @param target: 目标和
    * @return: 目标和的索引数组
    */
   public int[] twoSum(int[] nums, int target) {
-    return new int[]{1,2};
+    return new int[]{1, 2};
   }
 
+  public double findMedianSortedArrays(int[] nums1, int[] nums2) {
+    if(nums1.length == 0){
+      if(nums2.length % 2 == 0){
+        return (nums2[nums2.length/2]+nums2[nums2.length/2-1])/2.0;
+      }else{
+        return nums2[nums2.length/2];
+      }
+    }else if(nums2.length == 0){
+      if(nums1.length % 2 == 0){
+        return (nums1[nums1.length/2]+nums1[nums1.length/2-1])/2.0;
+      }else{
+        return nums1[nums1.length/2];
+      }
+    }
+
+    int[] A = nums1, B = nums2;
+    double median = 0.0, maxLeft = 0.0, minRight = 0.0;
+    if (nums1.length > nums2.length) {
+      A = nums2;
+      B = nums1;
+    }
+    int imin = 0, imax = A.length, i, j, halfLength = (A.length + B.length + 1) / 2;
+    while (imin <= imax) {
+      i = (imin + imax) / 2;
+      j = halfLength - i;
+      if (i < A.length && B[j - 1] > A[i]) {
+        imin = i + 1;
+      } else if (i > 0  && A[i - 1] > B[j]) {
+        imax = i - 1;
+      } else {
+        if (i == 0) {
+          maxLeft = B[j - 1];
+        } else if (j == 0) {
+          maxLeft = A[i - 1];
+        } else {
+          maxLeft = A[i - 1] > B[j - 1] ? A[i - 1] : B[j - 1];
+        }
+
+        if (i == A.length) {
+          minRight = B[j];
+        } else if (j == B.length) {
+          minRight = A[i];
+        } else {
+          minRight = A[i] < B[j] ? A[i] : B[j];
+        }
+
+        if ((A.length + B.length) % 2 == 1)
+          median = maxLeft;
+        else
+          median = (maxLeft + minRight) / 2;
+
+        break;
+      }
+    }
+    return median;
+  }
 }

Java/src/test/java/com/supercoderhawk/Solution_1_10Test.java

@@ -0,0 +1,27 @@
+package com.supercoderhawk;
+
+
+import org.junit.Before;
+import org.junit.Test;
+import com.supercoderhawk.Solution_1_10;
+
+import static org.junit.Assert.*;
+
+public class Solution_1_10Test {
+  private Solution_1_10 solution = new Solution_1_10();
+
+  @Test
+  public void twoSum() throws Exception {
+  }
+
+  @Test
+  public void findMedianSortedArrays() throws Exception {
+    int[] a1={1},a2={2,3};
+    assertEquals(2.0,solution.findMedianSortedArrays(a1,a2),0.0);
+    assertEquals(1.0,solution.findMedianSortedArrays(new int[]{1},new int[]{}),0.0);
+    assertEquals(1.5,solution.findMedianSortedArrays(new int[]{1},new int[]{2}),0.0);
+    assertEquals(3.0,solution.findMedianSortedArrays(new int[]{1},new int[]{2,3,4,5}),0.0);
+    assertEquals(4.0,solution.findMedianSortedArrays(new int[]{5,6},new int[]{1,2,3,4,7}),0.0);
+  }
+
+}