merge_sorted_array.py

#!/usr/bin/env python
# encoding: utf-8
"""
merge_sorted_array.py

Created by Shengwei on 2014-07-15.
"""

# https://oj.leetcode.com/problems/merge-sorted-array/
# tags: easy / medium, array, sorted, merge

"""
Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note:
You may assume that A has enough space (size that is greater or equal to m + n) to hold additional elements from B. The number of elements initialized in A and B are m and n respectively.
"""

class Solution:
    # @param A  a list of integers
    # @param m  an integer, length of A
    # @param B  a list of integers
    # @param n  an integer, length of B
    # @return nothing
    def merge(self, A, m, B, n):
        i, j, k = m - 1, n - 1, m + n - 1
        
        while i >= 0 and j >= 0:
            if A[i] > B[j]:
                A[k] = A[i]
                i -= 1
            else:
                A[k] = B[j]
                j -= 1
            k -= 1
        
        if i < 0:
            # A has been merged, move left B to A
            while j >= 0:
                A[k] = B[j]
                j -= 1
                k -= 1