Topic
- Array
Description
https://leetcode.com/problems/reshape-the-matrix/
In MATLAB, there is a handy function called reshape which can reshape an m x n matrix into a new one with a different size r x c keeping its original data.
You are given an m x n matrix mat and two integers r and c representing the row number and column number of the wanted reshaped matrix.
The reshaped matrix should 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: mat = [[1,2],[3,4]], r = 1, c = 4
Output: [[1,2,3,4]]
Example 2:
Input: mat = [[1,2],[3,4]], r = 2, c = 4
Output: [[1,2],[3,4]]
Constraints:
- m == mat.length
- n == mat[i].length
- 1 <= m, n <= 100
- -1000 <= mat[i][j] <= 1000
- 1 <= r, c <= 300
Analysis
略
Submission
public class ReshapeTheMatrix {
public int[][] matrixReshape(int[][] mat, int r, int c) {
if(mat.length * mat[0].length != r * c)
return mat;
int[][] result = new int[r][c];
int rp = 0, cp = 0;
for(int[] array : mat)
for(int i : array) {
result[rp][cp++] = i;
if(cp == c) {
rp++;
cp = 0;
}
}
return result;
}
}
Test
import static org.junit.Assert.*;
import org.junit.Test;
public class ReshapeTheMatrixTest {
@Test
public void test() {
ReshapeTheMatrix obj = new ReshapeTheMatrix();
int[][] result1 = obj.matrixReshape(new int[][] {{1, 2}, {3, 4}}, 1, 4);
int[][] expected1 = {{1, 2, 3, 4}};
for(int i = 0; i < expected1.length; i++)
assertArrayEquals(expected1[i], result1[i]);
int[][] result2 = obj.matrixReshape(new int[][] {{1, 2}, {3, 4}}, 2, 4);
int[][] expected2 = {{1, 2}, {3, 4}};
for(int i = 0; i < expected2.length; i++)
assertArrayEquals(expected2[i], result2[i]);
}
}