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//
// Challenge
//
// You are given an array of positive integers @N.
//
// Write a script to return an array @M where $M[i] is the product of
// all elements of @N except the index $N[i].
//
//
// We first calculate the result for M [0], by multiplying all
// numbers N [1 ..]. Then, for each i > 0, we calculate M [i] as
//
// M [i] = (M [i - 1] / N [i]) * N [i - 1]
//
// Assuming the challenge is created such that each M [i] fits in an
// integer, this will not result in an overflow, as long as we first do
// the division, then the multiplication.
// Note that N [i] evenly divides M [i - 1] by definition.
//
//
// Node.js doesn't have 64 bit integers. We need to explicitly make numbers
// into BigInt objects to deal with number larger than about 53 bits.
// And Node.js doesn't always cast numbers to BigInts with arithmetic.
//
//
// Read STDIN. Split on newlines, then on whitespace, and turn the results
// into (BigInt) numbers.
//
let lines = require ("fs")
. readFileSync (0) // Read all.
. toString () // Turn it into a string.
. split ("\n") // Split on newlines.
. filter (_ => _ . length) // Filter empty lines.
. map (_ => _ . split (" ") // Split lines
// on spaces
. map (_ => BigInt (_))) // Numify.
;
//
// Iterate over the lines
//
lines . forEach (array => {
//
// Get the first product
//
let product = array . reduce ((acc, val, idx) => {
return idx ? acc * val : 1n;
}, 1);
//
// Print it
//
process . stdout . write ("" + product);
//
// Get the other products
//
array . forEach ((val, idx, array) => {
if (idx) {
product = product / array [idx];
product = product * array [idx - 1];
process . stdout . write (", " + product);
}
});
process . stdout . write ("\n");
});
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