88. Merge Sorted Array

Two Pointers

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class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int endIndex = nums1.length - 1;

        int i = m - 1, j = n - 1;

        while (i >= 0 && j >= 0) {
            if (nums1[i] >= nums2[j]) {
                nums1[endIndex] = nums1[i--];
            } else {
                nums1[endIndex] = nums2[j--];
            }
            endIndex--;
        }

        while (i >= 0) {
            nums1[endIndex--] = nums1[i--];
        }
        while (j >= 0) {
            nums1[endIndex--] = nums2[j--];
        }
    }
}

Two Pointers

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class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int curr = m + n - 1;
        int index1 = m - 1, index2 = n - 1;

        while (curr >= 0) {
            int num1 = index1 >= 0 ? nums1[index1] : Integer.MIN_VALUE;
            int num2 = index2 >= 0 ? nums2[index2] : Integer.MIN_VALUE;

            // 注意较大值放末尾
            if (num1 >= num2) {
                nums1[curr] = num1;
                index1--;
            } else {
                nums1[curr] = num2;
                index2--;
            }
            curr--;
        }
    }
}

References

88. Merge Sorted Array