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  1. Prepare
  2. Algorithms
  3. Recursion
  4. Arithmetic Expressions
  5. Discussions

Arithmetic Expressions

  • cafelatte
     + 0 comments

    Despite this problem being in the category "Recursion", I feel it much more appropriate to use DP.

    Here what that looks like in Python3:

    def arithmeticExpressions(arr):
    this = [None] * 101
    this[arr[0]] = [arr[0]]
    for a in arr[1:]:
        if this[0]:
            this[0] += ['*', a]
        else:
            that = [None] * 101
            for i, v in enumerate(this):
                if v is not None:
                    that[(i+a)%101] = this[i] + ['+', a]
                    that[(i-a)%101] = this[i] + ['-', a]
                    that[(i*a)%101] = this[i] + ['*', a]
            this = that
    return ''.join(map(str, this[0]))