问题描述:
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 ] ]
原问题链接:https://leetcode.com/problems/spiral-matrix-ii/
问题分析
这个问题和前面的Spiral Matrix 基本上差不多,前面是要求按照这种方式遍历整个矩阵,这里是按照这个方式给矩阵里的元素赋值。所以可以在原来的基础上稍微修改一点直接搬过来就可以了。详细的代码实现如下:
public class Solution {
public int[][] generateMatrix(int n) {
int[][] matrix = new int[n][n];
int rowBegin = 0, rowEnd = n - 1, colBegin = 0, colEnd = n - 1, count = 1;
while(rowBegin <= rowEnd && colBegin <= colEnd) {
for(int i = colBegin; i <= colEnd; i++) {
matrix[rowBegin][i] = count;
count++;
}
rowBegin++;
for(int i = rowBegin; i <= rowEnd; i++) {
matrix[i][colEnd] = count;
count++;
}
colEnd--;
if(rowBegin <= rowEnd) {
for(int i = colEnd; i >= colBegin; i--) {
matrix[rowEnd][i] = count;
count++;
}
}
rowEnd--;
if(colBegin <= colEnd) {
for(int i = rowEnd; i >= rowBegin; i--) {
matrix[i][colBegin] = count;
count++;
}
}
colBegin++;
}
return matrix;
}
}