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Created July 19, 2015 10:36
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JS Bin // source http://jsbin.com/yetubi
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<script src="https://cdn.rawgit.com/lodash/lodash/3.0.1/lodash.min.js"></script>
<meta charset="utf-8">
<title>JS Bin</title>
</head>
<body>
<script id="jsbin-javascript">
/**
* This script finds 4 whole number values that have a specific relationship.
* Specifically, the sum of the squares of 3 numbers when they equal the
* square root of the 4th number. In linear algebra terms, this calculates
* the absolute value of a vector [x, y, z] when all values and the result
* are whole numbers. This formula is also known to calculate the distance
* of a 3D point from zero: d = sqrt(x*x + y*y + z*z)
*
* I recognize it's totally silly, but I wrote this because I was writing a
* unit test for a function that performs this calculation and I wanted my
* test cases to be whole numbers. This is how I found them.
*
* skip controls the smallest value in the vector
* start and stop control the range of distance, d
*/
'use strict';
console.clear();
var skip = 2;
var start = 9;
var stop = 100;
var getNext = function getNext(_x, _x2, _x3) {
var _again = true;
_function: while (_again) {
var arr = _x,
target = _x2,
result = _x3;
current = next = slice = undefined;
_again = false;
if (arr.length === 0) return result;
var current = _.last(arr);
result.push(current);
var next = target - current;
var slice = _.filter(arr, function (i) {
return i <= next;
});
_x = slice;
_x2 = next;
_x3 = result;
_again = true;
continue _function;
}
};
var getAnswer = function getAnswer(num) {
var target = Math.pow(num, 2);
var square = function square(val) {
return Math.pow(val, 2);
};
var squares = _.range(skip, num).map(square);
var maybe = getNext(squares, target, []);
var check = _.reduce(maybe, function (total, i) {
return total + i;
});
if (maybe.length === 3 && check === target) {
console.log(num + ': ' + _.map(maybe, Math.sqrt));
}
};
_.range(start, stop).map(getAnswer);
</script>
<script id="jsbin-source-javascript" type="text/javascript">/**
* This script finds 4 whole number values that have a specific relationship.
* Specifically, the sum of the squares of 3 numbers when they equal the
* square root of the 4th number. In linear algebra terms, this calculates
* the absolute value of a vector [x, y, z] when all values and the result
* are whole numbers. This formula is also known to calculate the distance
* of a 3D point from zero: d = sqrt(x*x + y*y + z*z)
*
* I recognize it's totally silly, but I wrote this because I was writing a
* unit test for a function that performs this calculation and I wanted my
* test cases to be whole numbers. This is how I found them.
*
* skip controls the smallest value in the vector
* start and stop control the range of distance, d
*/
console.clear()
const skip = 2
const start = 9
const stop = 100
var getNext = (arr, target, result) => {
if(arr.length === 0) return result
const current = _.last(arr)
result.push(current)
const next = target - current
const slice = _.filter(arr, (i) => { return i <= next })
return getNext(slice, next, result)
}
var getAnswer = (num) => {
const target = Math.pow(num, 2)
const square = (val) => { return Math.pow(val, 2) }
const squares = _.range(skip, num).map(square)
const maybe = getNext(squares, target, [])
const check = _.reduce(maybe, (total, i) => total + i)
if(maybe.length === 3 && check === target) {
console.log(num + ': '+ _.map(maybe, Math.sqrt))
}
}
_.range(start, stop).map(getAnswer)
</script></body>
</html>
Raw
jsbin.yetubi.js
/**
* This script finds 4 whole number values that have a specific relationship.
* Specifically, the sum of the squares of 3 numbers when they equal the
* square root of the 4th number. In linear algebra terms, this calculates
* the absolute value of a vector [x, y, z] when all values and the result
* are whole numbers. This formula is also known to calculate the distance
* of a 3D point from zero: d = sqrt(x*x + y*y + z*z)
*
* I recognize it's totally silly, but I wrote this because I was writing a
* unit test for a function that performs this calculation and I wanted my
* test cases to be whole numbers. This is how I found them.
*
* skip controls the smallest value in the vector
* start and stop control the range of distance, d
*/
'use strict';
console.clear();
var skip = 2;
var start = 9;
var stop = 100;
var getNext = function getNext(_x, _x2, _x3) {
var _again = true;
_function: while (_again) {
var arr = _x,
target = _x2,
result = _x3;
current = next = slice = undefined;
_again = false;
if (arr.length === 0) return result;
var current = _.last(arr);
result.push(current);
var next = target - current;
var slice = _.filter(arr, function (i) {
return i <= next;
});
_x = slice;
_x2 = next;
_x3 = result;
_again = true;
continue _function;
}
};
var getAnswer = function getAnswer(num) {
var target = Math.pow(num, 2);
var square = function square(val) {
return Math.pow(val, 2);
};
var squares = _.range(skip, num).map(square);
var maybe = getNext(squares, target, []);
var check = _.reduce(maybe, function (total, i) {
return total + i;
});
if (maybe.length === 3 && check === target) {
console.log(num + ': ' + _.map(maybe, Math.sqrt));
}
};
_.range(start, stop).map(getAnswer);
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