leetcode 321 Create Maximum Number
z
 2019-04-09 10:36:27  

Given two arrays of length m and n with digits 0-9representing two numbers. Create the maximum number of length k <= m + n from digits of the two. The relative order of the digits from the same array must be preserved. Return an array of the k digits.

Note: You should try to optimize your time and space complexity.

Example 1:

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Input:
nums1 = [3, 4, 6, 5]
nums2 = [9, 1, 2, 5, 8, 3]
k = 5
Output:
[9, 8, 6, 5, 3]

Example 2:

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Input:
nums1 = [6, 7]
nums2 = [6, 0, 4]
k = 5
Output:
[6, 7, 6, 0, 4]

Example 3:

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Input:
nums1 = [3, 9]
nums2 = [8, 9]
k = 3
Output:
[9, 8, 9]
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public class CreateMaximumNumber {

    public int[] maxNumber(int[] nums1, int[] nums2, int k) {
        int m = nums1.length;
        int n = nums2.length;
        int[] result = new int[k];
        if (m + n < k) return result;
        else if (m+n == k) {
            result = merge(nums1, nums2);
            return result;
        }
        else {
            for (int i=1; i<=k; i++) {
                if (i<nums1.length && k-i < nums2.length) {
                    int[] l1 = largestK(nums1, i);
                    int[] l2 = largestK(nums2, k-i);
                    int[] total = merge(l1, l2);
                    if (isLarger(total, result))
                        result = total;
                }

            }
        }
        return result;
    }
    public boolean isLarger(int[] current, int[] old) {
        for(int i=0; i<current.length; i++) {
            if (current[i] > old[i])
                return true;
        }
        return false;
    }

    public int[] largestK(int[] nums, int k) {
        int t = 0;
        int[] ans = new int[k];
        for (int i=0; i<nums.length; i++) {
            int remain = nums.length - i - 1;
            while (remain + (t+1) > k && t > 0 && nums[i] > ans[t-1]) {
                t --;
            }
            if (t < k)
                ans[t++] = nums[i];
        }
        return  ans;
    }

    public int[] merge(int[] nums1, int[] nums2) {
        int i=0;
        int j=0;
        int t=0;
        int [] result = new int[nums1.length + nums2.length];
        while (i < nums1.length || j < nums2.length) {
            if (i >= nums1.length) {
                result[t++] = nums2[j++];
            }
            else if (j >= nums2.length) {
                result[t++] = nums1[i++];
            }
            else if (nums1[i] < nums2[j]) {
                result[t++] = nums2[j++];
            }
            else {
                result[t++] = nums1[i++];
            }
        }
        return result;
    }

}