<LeetCode>566. Reshape the Matrix

566. Reshape the Matrix

In MATLAB, there is a very useful function called 'reshape', which can reshape a matrix into a new one with different size but keep its original data.

You're given a matrix represented by a two-dimensional array, and two positive integers r and c representing the row number and column number of the wanted reshaped matrix, respectively.

The reshaped matrix need to be filled with all the elements of the original matrix in the same row-traversing order as they were.

If the 'reshape' operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.

Example 1:

Input: nums = [[1,2], [3,4]]r = 1, c = 4Output: [[1,2,3,4]]Explanation:
The row-traversing of nums is [1,2,3,4]. The new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the previous list.

Example 2:

Input: nums = [[1,2], [3,4]]r = 2, c = 4Output: [[1,2], [3,4]]Explanation:
There is no way to reshape a 2 * 2 matrix to a 2 * 4 matrix. So output the original matrix.

Note:

1. The height and width of the given matrix is in range [1, 100].
2. The given r and c are all positive.

题目大意：

给定一个二维数组，再给定一个r,c。

求将这个二维数组转换为一个R*C的数组（原数组按行遍历）（如果合法即转换，如果不合法，就返回原数组）

思路：

如果原数组的长度和新数组（r*c）的长度是一致的，那就可以转换成功；遍历r,c，将原数组都赋值给他就可以

如果长度不一致，直接返回原数组

class Solution {    public int[][] matrixReshape(int[][] nums, int r, int c) {        //int[][] nums = {{1,2},{3,4}};        List<Integer> list = new ArrayList<Integer>();        //int r = 1,c = 4;//        System.out.println(nums.length*nums[0].length);//长度表示，其中一定为n*m数组？？        //如果不为n*m的数组？？？        int count = 0,len =  0;        for (int i = 0; i < nums.length; i++) {            for (int j = 0; j < nums[i].length; j++) {                count++;                list.add(nums[i][j]);            }        }        System.out.println(count);        int[][] solu = new int [r][c];        if(c*r==count){            for (int i = 0; i < r; i++) {                for (int j = 0; j < c; j++) {                    solu[i][j] = list.get(len++);                }            }            return solu;        }else{            return nums;        }    }}