INLO34 - Editorial

PROBLEM LINK:

Practice
Contest

Author: RAVIT SINGH MALIK
Editorialist: RAVIT SINGH MALIK

DIFFICULTY:

EASY

PREREQUISITES:

MATHS,NUMBER THEORY

PROBLEM:

Find the number of ways of selecting one or more items from N distinct things.

EXPLANATION:

So, Number of ways of selecting one or more items from N distinct things.

nC0 + nC1 + nC2 + nC3 + ------------- + nCn = 2^n

nC1 + -----------------nCn =2^n - nC0

= 2^n – 1 , [ nC0=1]

FOR example,
you need to find number of ways of selecting one or more items from 5 distinct things.
so,

5C0 + 5C1 + 5C2 + 5C3 + 5C4 + 5C5 = 2^5

5C1 + 5C2 + 5C3 + 5C4 + 5C5 =2^n - 5C0

= 2^5 – 1=31

AUTHOR’S AND TESTER’S SOLUTIONS:

Author’s solution can be found here.

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