Java 顺时针打印矩阵

题目描述

对于一个矩阵，请设计一个算法从左上角(mat[0][0])开始，顺时针打印矩阵元素。

给定int矩阵mat,以及它的维数nxm，请返回一个数组，数组中的元素为矩阵元素的顺时针输出。

测试样例：

[[1,2],[3,4]],2,2

返回：[1,2,4,3]

    public static void main(String[] args) {        int m = 5;        int n = 7;        int mat [][] = new int[n][m];        int temp = 0;        for (int a = 0 ; a < n;a++){            for(int j = 0; j < m; j++){                mat[a][j] = temp;                System.out.print(temp+"\t");                temp++;            }            System.out.println();        }        calc(mat,n,m);    }    public static void calc(int[][] mat, int n, int m){//m 列 n行        List<Integer> lists = new ArrayList<Integer>();        class Point{            int x;            int y;            public Point(int x,int y){                this.x = x;                this.y = y;            }        }        List<Point> up_left = new ArrayList<Point>();        List<Point> up_right = new ArrayList<Point>();        List<Point> down_left = new ArrayList<Point>();        List<Point> down_right = new ArrayList<Point>();        //如果 矩阵是胖的 或者是正方形 ，就是行数 小于 列数，或者 行数等于 列数        if(m >= n){            int row = n%2 == 1?n/2+1:n/2;            int row_down = n/2;            for (int i = 0 ; i < row ; i++){                up_left.add(new Point(i,i));                up_right.add(new Point(i,m-1-i));            }            for(int i = 0 ; i < row_down ; i++){                down_left.add(new Point(n-1-i,i));                down_right.add(new Point(n-1-i,m-1-i));            }            for (int i = 0 ; i < up_left.size() ; i++){                Point upleft = up_left.get(i);                Point upright = up_right.get(i);                Point downleft =  null;                Point downright = null;                if(i <= row_down - 1){                    downleft = down_left.get(i);                    downright = down_right.get(i);                }                for(int a = upleft.y;a <= upright.y ; a++){                    lists.add(mat[upleft.x][a]);                    System.out.print(mat[upleft.x][a]+"\t");                }                if(downleft != null){                    for(int a = upright.x+1;a <= downright.x ; a++){                        lists.add(mat[a][upright.y]);                        System.out.print(mat[a][upright.y]+"\t");                    }                    for(int a = downright.y-1;a >= downleft.y ; a--){                        lists.add(mat[downright.x][a]);                        System.out.print(mat[downright.x][a]+"\t");                    }                    for(int a = downleft.x-1;a >= upleft.x+1 ; a--){                        lists.add(mat[a][downleft.y]);                        System.out.print(mat[a][downleft.y]+"\t");                    }                }            }        }        //是瘦的 行数大于列数        else{            int col = m%2 == 1?m/2+1:m/2;            int col_down = m/2;            for (int i = 0 ; i < col ; i++){                up_left.add(new Point(i,i));                down_left.add(new Point(n-1-i,i));            }            for(int i = 0 ; i < col_down ; i++){                up_right.add(new Point(i,m-1-i));                down_right.add(new Point(n-1-i,m-1-i));            }            for (int i = 0 ; i < up_left.size(); i++){                Point upleft = up_left.get(i);                Point downleft =  down_left.get(i);                Point upright = null;                Point downright = null;                if(i <= col_down - 1){                    upright = up_right.get(i);                    downright = down_right.get(i);                }                if(upright != null){                    for(int a = upleft.y;a <= upright.y ; a++){                        lists.add(mat[upleft.x][a]);                        System.out.print(mat[upleft.x][a]+"\t");                    }                    for(int a = upright.x+1;a <= downright.x ; a++){                        lists.add(mat[a][upright.y]);                        System.out.print(mat[a][upright.y]+"\t");                    }                    for(int a = downright.y-1;a >= downleft.y ; a--){                        lists.add(mat[downright.x][a]);                        System.out.print(mat[downright.x][a]+"\t");                    }                    for(int a = downleft.x-1;a >= upleft.x+1 ; a--){                        lists.add(mat[a][downleft.y]);                        System.out.print(mat[a][downleft.y]+"\t");                    }                }else{                    for(int a = upleft.x;a <= downleft.x ; a++){                        lists.add(mat[a][upleft.y]);                        System.out.print(mat[a][upleft.y]+"\t");                    }                }            }        }        int result [] = new int[m*n];        for (int j = 0;j<lists.size();j++){            result[j] = lists.get(j);            //System.out.print(result[j]+"\t");        }        System.out.println(result);        return result;    }