leetcode: 27. Remove Element

数组元素移除算法

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本文介绍了一种在不使用额外空间的情况下从数组中移除指定值的算法，并保持了常数级别的内存消耗。通过实例展示了如何实现该算法，并提供了Python代码实现及验证。

Problem

# Given an array and a value, 
# remove all instances of that value in place and return the new length.
#
# Do not allocate extra space for another array, 
# you must do this in place with constant memory.
#
# The order of elements can be changed. 
# It doesn't matter what you leave beyond the new length.
#
# Example:
# Given input array nums = [3,2,2,3], val = 3
#
# Your function should return length = 2, with the first two elements of nums being 2.

AC

class Solution():
    def removeElement(self, x, val):
        cur = 0
        for _ in range(len(x)):
            if x[cur] == val:
                del x[cur]
            else:
                cur += 1
        return len(x)


if __name__ == "__main__":
    assert Solution().removeElement([3, 2, 2, 3], 3) == 2
    assert Solution().removeElement([1, 2, 3, 4, 5, 2, 2], 2) == 4