[Cracking The Coding Interview] 1.8: Zero Matrix

[jtkaufman737]

1.8 Zero Matrix

Write an algorithm such that if an element in an MXN matrix is 0, its entire row and column are set to zero

[jtkaufman737]

This is perhaps my least favorite solution to any of the CTCI problems I've had thus far but I wanted to move on so here we are.

function zeroMatrix(m) {
  let newArr = [], indexes = [];

  // copy original because I'm having stupid mutability issues
  for(let i=0; i < m.length; i++) {
    newArr.push([]);
    for(let j=0; j < m[i].length; j++) {
      newArr[i][j] = m[i][j];
    }
  }

  for(let i=0; i < m.length; i++) { 
    if(m[i].includes(0)) {              // head off unnecessary looping 
      for(let j=0; j < m[i].length; j++) { // items in row       
        newArr[i][j] = 0; // set each to 0 
        m[i][j] === 0 ? indexes.push(j) : '';
      }
    }
  }

  for(let i=0; i < m.length; i++) {
    for(let j=0; j < indexes.length; j++) {
      let key = indexes[j];
      newArr[i][key] = 0;
    }
  }

  console.log("Old array vs new array:");
  console.log(m);
  console.log(newArr);
}

zeroMatrix([[1,1,1],[0,2,0],[3,4,5]]) // end should be [0,1,0][0,0,0][0,4,0]