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# Python | Multiplication till Null value

• Last Updated : 19 Feb, 2020

The prefix array is quite famous in the programming world. This article would discuss a variation of this scheme. This deals with the cumulative list product till a False value, and again starts cumulation of product from occurrence of True value. Let’s discuss certain way in which this can be performed.

Method #1 : Using Naive Method
In the naive method, we just construct the new list comprising of the the product of prev. value of list until False and restarts the procedure once a True value is encountered.

 `# Python3 code to demonstrate ``# Multiplication till Null value``# using naive method `` ` `# initializing list of lists``test_list ``=` `[``1``, ``3``, ``4``, ``False``, ``4``, ``5``, ``False``, ``7``, ``8``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# Multiplication till Null value``# using naive method``for` `i ``in` `range``(``1``, ``len``(test_list)):``    ``if` `test_list[i]: ``        ``test_list[i] ``*``=` `test_list[i ``-` `1``]``    ``else``:``        ``test_list[i] ``=` `1`` ` `# printing result``print` `(``"The computed modified new list : "` `+` `str``(test_list))`
Output :
```The original list is : [1, 3, 4, False, 4, 5, False, 7, 8]
The computed modified new list : [1, 3, 12, 1, 4, 20, 1, 7, 56]
```

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