[Algorithmic] rotation matrix problem (Spiral matrix)

Topic One:

Given a matrix of m x n elements (m rows, n columns), return all elements of the Matri X in Spiral Order.

For example,
Given the following matrix:

[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

You should return [1,2,3,6,9,8,7,4,5] .

Answer:

A method that operates from the outermost layer to the inside.

 Public classSolution { PublicList<integer> Spiralorder (int[] matrix) {List<Integer> res =NewArraylist<>(); if(matrix==NULL|| matrix.length==0| | matrix[0].length==0)returnRes; //The coordinates of the number in the upper left corner of each lap are (top,left), the coordinates of the number in the lower right corner are (bottom,right)        inttop = 0, left = 0; intBottom = matrix.length-1, right = Matrix[0].length-1;  while(Top <= Bottom && left <=Right ) {Outedge (res, matrix, left+ +, top++, right--, bottom--); }        returnRes; }      Private Static voidOutedge (list<integer> Res,int[] Matrix,intLeftintTopintRightintbottom) {        if(top = =bottom) {             for(inti = left; I <= right; i++) {Res.add (matrix[top][i]); }        } Else if(left = =Right ) {             for(inti = top; I <= bottom; i++) {Res.add (matrix[i][left]); }        } Else {            intCurrow =top; intCurcol =Left ;  while(Curcol <Right ) {Res.add (Matrix[top][curcol++]); }             while(Currow <bottom) {Res.add (Matrix[currow++][right]); }             while(Curcol >Left ) {Res.add (Matrix[bottom][curcol--]); }             while(Currow >top) {Res.add (Matrix[currow--][left]); }        }    }}

Topic Two:

Given an integer n, generate a square matrix filled with elements from 1 to n2 in Spiral order.

For example,
Given N = 3 ,

You should return the following matrix:

[[1, 2, 3], [8, 9, 4], [7, 6, 5]]

 Public Static int[] Generatematrix (intN) {int[] res =New int[N][n]; inttop = 0, left = 0; intBottom = n-1, right = N-1; intnum = 1;  while(left<=right&&top<=bottom) {num= Inputedge (num, res, left++, top++, right--, bottom--); }        returnRes; }    Private Static intInputedge (intNumint[] Res,intLeftintTopintRightintbottom) {        intCurrow =top; intCurcol =Left ; if(top==bottom&&left==Right ) {Res[top][left]=num; returnnum; }         while(Curcol <Right ) {Res[top][curcol+ +] = num++; }         while(Currow <bottom) {Res[currow++][right] = num++; }         while(Curcol >Left ) {Res[bottom][curcol--] = num++; }         while(Currow >top) {Res[currow--][left] = num++; }        returnnum; }

[Algorithmic] rotation matrix problem (Spiral matrix)