4. 寻找两个正序数组的中位数

  public double findMedianSortedArrays(int[] nums1, int[] nums2) {
        //num1,num2的游标
        int num1Index=0,num2Index=0;
        int num1Length=nums1.length,num2Length=nums2.length;

        int totalLength= nums1.length+nums2.length;
        int avgIndex= (int) Math.ceil(new Double(totalLength)/2);
        //如果总长度是偶数则取第avgIndex和第avgIndex+1个数的平均数，如果是奇数则取第avgIndex个数的数

        int left=0,right=0;
        for (int i = 0,end=((totalLength&1)==1)?avgIndex:avgIndex+1; i <end ; i++) {
            left=right;
            if (num1Index==num1Length){
                right=nums2[num2Index++];
            }else if (num2Index==num2Length){
                right=nums1[num1Index++];
            }else {
                right=nums1[num1Index]<nums2[num2Index]?nums1[num1Index++]:nums2[num2Index++];
            }
        }

        if ((totalLength&1)==1){
            return new Double(right);
        }else {
            return new Double(right+left)/2;
        }
    }