LeetCode 59.Spiral Matrix || (Medium)

原题地址：https://leetcode.com/problems/spiral-matrix-ii/description/

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题目描述：
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 ]
]

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题解：
给出一个整型n，创建一个大小按顺时针增长的行列均为n的矩阵。解法和上一题相同，在已知n的情况下只需创建一个n*n的空矩阵，再按打印的方法将数字填进去就行。

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代码：

class Solution {public:    vector<vector<int>> generateMatrix(int n) {        if (n == 0) return  vector<vector<int>>();        int x = 0, y = 0;        int cntNumber = n*n;        int count = 0, queryNum = 0;        vector<vector<int>> output(n, vector<int>(n));        while (true) {            for (; y < n - queryNum; y++) {                output[x][y] = ++count;            }            y--;            x++;            if (count == cntNumber) break;            for (; x < n - queryNum; x++) {                output[x][y] = ++count;            }            x--;            y--;            if (count == cntNumber) break;            for (; y >= queryNum; y--) {                output[x][y] = ++count;            }            y++;            x--;            if (count == cntNumber) break;            for (; x > queryNum; x--) {                output[x][y] = ++count;            }            x++;            y++;            if (count == cntNumber) break;            queryNum++;        }        return output;    }};

21 / 21 test cases passed.
Status: Accepted
Runtime: 3 ms