【leetcode】4. Median of Two Sorted Arrays

计算中间两个数的平均值

没被hard难住，这题就是归并排序的应用，注意空指针

public class Solution {
    public double findMedianSortedArrays(int[] nums1, int[] nums2) {
        int length = length(nums1) + length(nums2);
        boolean isOdd = (length & 1) == 1;
        int left = 0;
        int right = 0;
        
        int middleRight = length / 2;
        int middleLeft = isOdd ? middleRight : middleRight - 1;
        
        int middleLeftValue = 0;
        int middleRightValue = 0;
        
        for (int i = 0; i <= middleRight && i < length; ++i) {
            int leftValue = get(nums1, left);
            int rightValue = get(nums2, right);
            if (leftValue <= rightValue) {
                left++;
                if (i == middleLeft) {
                    middleLeftValue = leftValue;
                }
                if (i == middleRight) {
                    middleRightValue = leftValue;
                }
            } else {
                right++;
                if (i == middleLeft) {
                    middleLeftValue = rightValue;
                }
                if (i == middleRight) {
                    middleRightValue = rightValue;
                }
            }
        }
        
        return (middleLeftValue + middleRightValue) * 1.0 / 2;
    }
    
    private int length(int[] num) {
        return num == null ? 0 : num.length;
    }
    
    private int get(int[] nums, int index) {
        if (nums == null || index >= nums.length) {
            return Integer.MAX_VALUE;
        } else {
            return nums[index];
        }
    }
}