螺旋矩阵变式

/**
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function(n) {
    let matrix=new Array(n).fill(0).map(item=>new Array(n).fill(0))
    let indx = 1
    let i1,i2,j1,j2
    i1 = 0 //从左到右
    i2 = n-1
    j1 = 0 //从上到下
    j2 = n-1
    while(true){
      for(let i = i1;i<=i2;i++){
        matrix[i1][i] = indx++
      }
      if(indx > n*n){
        break
      }
      j1++
      for(let i = j1;i<=j2;i++){
        matrix[i][i2] = indx++
      }
      if(indx > n*n){
        break
      }
      j2--
      for(let i = j2;i>=i1;i--){ //从右往左
        matrix[i2][i] = indx++
      }
      if(indx > n*n){
        break
      }
      i2--
      for(let i = i2;i>=j1;i--){ //从下往上
        matrix[i][i1] = indx++
      }
      if(indx > n*n){
        break
      }
      i1++
    }
    let res = []
    for(let i=0;i<n;i++){
      let temp = []
      for(let j=0;j<n;j++){
        temp.push(matrix[i][j])
      }
      res.push(temp)
    }
    return res
};