Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
Example:
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Input: 3
Output:
[
[ 1, 2, 3 ],
[ 8, 9, 4 ],
[ 7, 6, 5 ]
]
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解法
之前的那道题是螺旋形遍历数组，这题是螺旋形生成数组，方法都差不多，设置边界与方向，为二维数组赋值，同样注意处理1和0输入的情况。感觉第二次写这类题思路顺畅了很多呢(^_^)~
具体代码如下：
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class {
public int[][] generateMatrix(int n) {
int[][] res = new int[n][n];
if (n == 1) {
res[0][0] = 1;
return res;
}
int max = n * n;
int i = 0;
int j = 0;
int upbond = 0;
int lowbond = n - 1;
int leftbond = 0;
int rightbond = n - 1;
int dir = 0;
res[i][j] = 1;
for (int k = 2; k <= max; k++) {
switch (dir) {
case 0: {
j++;
res[i][j] = k;
if (j == rightbond) {
dir = 1;
upbond++;
}
break;
}
case 1: {
i++;
res[i][j] = k;
if (i == lowbond) {
dir = 2;
rightbond--;
}
break;
}
case 2: {
j--;
res[i][j] = k;
if (j == leftbond) {
dir = 3;
lowbond--;
}
break;
}
case 3: {
i--;
res[i][j] = k;
if (i == upbond) {
dir = 0;
leftbond++;
}
break;
}
}
}
return res;
}
}
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