90 Degree Matrix Rotation Clockwise & Counter-Clockwise

https://repl.it/@pantherhawk22/2D-Matrix-Rotation

// rotate 2d grid 90 degrees 

// o: 2d array rotated 90 degrees, counter clockwise
// i: 2d array, width = length
// c: no worse the O(n^2) 
// PLAN:
// reverse order of rows
// replace the last column elements of each row with elements in the first row, until you reach the next to last
// then replace second to last 
// 
//     [1,1,1],          [3, 3, 3],
//     [2,2,2],   == >   [2, 2, 2],
//     [3,3,3]           [1, 1, 1]
//   
// replace first row first column with last row last column
// [3, 3, 3],           [1, 3, 3],
// [2, 2, 2]     === >  [2, 2, 2]
// [1, 1, 1]            [1, 1, 3]

// replace first row second column with second row last column

// [1, 3, 3]           [1, 2, 3]              
// [2, 2, 2]   == >    [2, 2, 3]                      
// [1, 1, 3]           [1, 1, 3]   

var input1x1 = [
    [1]
  ]

var input3x3 = [
    [1, 1, 1],
    [2, 2, 2],
    [3, 3, 3]
  ]
var expectedCounterClockwise3x3 = [
    [1, 2, 3],
    [1, 2, 3],
    [1, 2, 3]
  ]
var expectedClockwise3x3 = [
    [ 3, 2, 1 ], 
    [ 3, 2, 1 ], 
    [ 3, 2, 1 ]
  ]

var input4x4 = [
    [1, 2, 3, 4],
    [1, 2, 3, 4],
    [1, 2, 3, 4],
    [1, 2, 3, 4]
  ]
  
var expectedClockwise4x4 = [
    [1, 1, 1, 1],
    [2, 2, 2, 2],
    [3, 3, 3, 3],
    [4, 4, 4, 4]
  ]
  
var expectedCounterClockwise4x4 = [ 
    [ 4, 4, 4, 4 ], 
    [ 3, 3, 3, 3 ], 
    [ 2, 2, 2, 2 ], 
    [ 1, 1, 1, 1 ] 
  ]
  
assert(rotateMtxClockwise(input4x4), expectedClockwise4x4, '90 degree clockwise rotation of 4x4 matrix');
assert(rotateMtxCounterClockwise(input4x4), expectedCounterClockwise4x4, '90 degree counter-clockwise rotation of 4x4 matrix');
assert(rotateMtxClockwise(input3x3), expectedClockwise3x3, '90 degree clockwise rotation of 3x3 matrix');
assert(rotateMtxCounterClockwise(input3x3), expectedCounterClockwise3x3, '90 degree counter-clockwise rotation of 3x3 matrix');
assert(rotateMtxClockwise(input1x1), input1x1, '90 degree clockwise rotation of 1x1 matrix');
assert(rotateMtxCounterClockwise(input1x1), input1x1, '90 degree counter-clockwise rotation of 1x1 matrix');


function rotateMtxClockwise(grid) {
  grid = grid.reverse();
  return grid.map((n, i) => {
    return n.map((m, j) => {
      return grid[j][i]
    })
  })
}

function rotateMtxCounterClockwise(grid) {
  grid = grid.reverse();
  return grid.map((row, i) => {
    return row.map((column, j) => {
      return grid[grid.length - 1 - j][grid.length - 1 - i]
    })
  })
}

function assert(a, b, caption) {
  let result = JSON.stringify(a) === JSON.stringify(b) ? ' SUCCEEDS.' : ' FAILS.';
  console.log(caption + result);
}