Method spiralMatrixIII

spiralMatrix3.java:2–30

(int rows, int cols, int rStart, int cStart)

class Solution {
    public int[][] spiralMatrixIII(int rows, int cols, int rStart, int cStart) {
        int directions[][] = {{0,1},{1,0},{0,-1},{-1,0}};
        int n = rows*cols;
        int res[][] = new int[n][2];//[[r,c],[r1,c1]...
        res[0][0] = rStart;
        res[0][1] = cStart;
        int count=1;
        int step=1;
        int index=0;
        
        while(count<n){
            for(int times=0;times<2;times++){
                int dr = directions[index%4][0];
                int dc = directions[index%4][1];
                for(int i=0;i<step;i++){
                    rStart+=dr;
                    cStart+=dc;
                    if(rStart>=0 && rStart<rows && cStart>=0 && cStart<cols){
                        res[count][0] = rStart;
                        res[count][1] = cStart;
                        count++;
                    }
                }
                index++;
            }
            step++;
        }
        return res;
    }
}