vSPARROW

leetcode : 867. Transpose Matrix

Posted on June 11, 2020

This one took a while to get. Originally I was trying to transpose in place, but you cannot guarantee the input is a square, so in place won’t work.Not sure if even in C you can transpose in place for a rectangular input. There maybe some memory tricks there, but they definitely are not available for JavaScript

Code is commented to guide

var transpose = function(A) {
    //this problem we actually cant transpose in place
    //since we cannot guarantee that the input is a square
    
    const result = []
    const rowsLength = A[0].length
    const columnsLength = A.length
    
    for(i=0;i<rowsLength;i++){
        let column = []
        for(j=0;j<columnsLength;j++){
            //here we get all elements in a column from input array A
            //and add it to new array named column
            column.push(A[j][i])
        }
        //we take the variable column we generated above
        //and turn it into a row for output Array result
        result.push(column)
    }
    return result
};