Created
March 6, 2018 01:55
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Flatten Integers
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| // FLATTEN INTEGERS ///////////////////////////////////////////////////////////////////// | |
| const flattenIntegers = ints => | |
| ///// Transforms nested lists of integers into a flat list of integers. | |
| ///// e.g. 1 -> error | |
| ///// e.g. [ 1 ] -> [1 ] | |
| ///// e.g. [[1,2,[3]],4] -> [1,2,3,4] | |
| { | |
| const concatLists = lists => | |
| ///// Transforms a list of lists into a single list. | |
| ///// e.g. [ 1 ] -> error | |
| ///// e.g. [[1,2],[3],[],[4]] -> [1,2,3,4] | |
| [].concat.apply( [], lists ); | |
| const flattenInteger = int => | |
| ///// Transforms a single integer or nested list of integers into a list of integers. | |
| ///// e.g. "1" -> error | |
| ///// e.g. 1.1 -> error | |
| ///// e.g. 1.0 -> [ 1 ] | |
| ///// e.g. 1 -> [ 1 ] | |
| ///// e.g. [ 1 ] -> [ 1 ] | |
| ///// e.g. [ 1, [ 2 ] ] -> [ 1, 2 ] | |
| { | |
| if( Number.isInteger( int ) ) | |
| return [ int ]; | |
| ////// This is our recursion base-case! | |
| ////// We ALWAYS want to return a list of integers. | |
| else if( Array.isArray( int ) ) | |
| return concatLists( int.map( flattenInteger ) ); | |
| ////// We transform each member of the list into a list of integers, and then concatenate them all together. | |
| else | |
| throw `flattenIntegers expected an array whose members are integers or lists of integers, but it received ${ JSON.stringify( int ) }`; | |
| }; | |
| if( Array.isArray( ints ) ) | |
| return concatLists( ints.map( flattenInteger ) ); | |
| ////// We transform each member of the list into a list of integers, and then concatenate them all together. | |
| else | |
| throw `flattenIntegers expected an array, but it received ${ JSON.stringify( ints ) }`; | |
| }; | |
| // VERIFICATION ///////////////////////////////////////////////////////////////////////// | |
| console.log( flattenIntegers( [[1,2,[3]],4] ) ); |
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