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Write a function that generates one of 3 numbers according to given probabilities
• Difficulty Level : Easy
• Last Updated : 14 Apr, 2021

You are given a function rand(a, b) which generates equiprobable random numbers between [a, b] inclusive. Generate 3 numbers x, y, z with probability P(x), P(y), P(z) such that P(x) + P(y) + P(z) = 1 using the given rand(a,b) function.
The idea is to utilize the equiprobable feature of the rand(a,b) provided. Let the given probabilities be in percentage form, for example P(x)=40%, P(y)=25%, P(z)=35%..

Following are the detailed steps.
1) Generate a random number between 1 and 100. Since they are equiprobable, the probability of each number appearing is 1/100.
2) Following are some important points to note about generated random number ‘r’.
a) ‘r’ is smaller than or equal to P(x) with probability P(x)/100.
b) ‘r’ is greater than P(x) and smaller than or equal P(x) + P(y) with P(y)/100.
c) ‘r’ is greater than P(x) + P(y) and smaller than or equal 100 (or P(x) + P(y) + P(z)) with probability P(z)/100.

## C

 `// This function generates 'x' with probability px/100, 'y' with``// probability py/100  and 'z' with probability pz/100:``// Assumption: px + py + pz = 100 where px, py and pz lie``// between 0 to 100``int` `random(``int` `x, ``int` `y, ``int` `z, ``int` `px, ``int` `py, ``int` `pz)``{      ``        ``// Generate a number from 1 to 100``        ``int` `r = ``rand``(1, 100);``     ` `        ``// r is smaller than px with probability px/100``        ``if` `(r <= px)``            ``return` `x;` `         ``// r is greater than px and smaller than or equal to px+py``         ``// with probability py/100``        ``if` `(r <= (px+py))``            ``return` `y;` `         ``// r is greater than px+py and smaller than or equal to 100``         ``// with probability pz/100``        ``else``            ``return` `z;``}`

## Python

 `import` `random` `# This function generates 'x' with probability px/100, 'y' with``# probability py/100  and 'z' with probability pz/100:``# Assumption: px + py + pz = 100 where px, py and pz lie``# between 0 to 100``def` `random(x, y, z, px, py, pz): ``    ` `    ``# Generate a number from 1 to 100``    ``r ``=` `random.randint(``1``, ``100``)``    ` `    ``#  r is smaller than px with probability px/100``    ``if` `(r <``=` `px):``        ``return` `x``    ` `    ``# r is greater than px and smaller than``    ``# or equal to px+py with probability py/100``    ``if` `(r <``=` `(px``+``py)):``        ``return` `y``        ` `    ``# r is greater than px+py and smaller than``    ``# or equal to 100 with probability pz/100``    ``else``:``        ``return` `z``    ` `# This code is contributed by rohan07`

This function will solve the purpose of generating 3 numbers with given three probabilities.