59. 螺旋矩阵 II

题目:给你一个正整数 n ,生成一个包含 1 到 n2 所有元素,且元素按顺时针顺序螺旋排列的 n x n 正方形矩阵 matrix 。 

示例 1:

输入:n = 3
输出:[[1,2,3],[8,9,4],[7,6,5]]

题解:

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        int maxNum = n * n;
        int curNum = 1;
        vector<vector<int>> matrix(n, vector<int>(n));
        int row = 0, column = 0;
        vector<vector<int>> directions = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};  // 右下左上
        int directionIndex = 0;
        while (curNum <= maxNum) {
            matrix[row][column] = curNum;
            curNum++;
            int nextRow = row + directions[directionIndex][0], nextColumn = column + directions[directionIndex][1];
            if (nextRow < 0 || nextRow >= n || nextColumn < 0 || nextColumn >= n || matrix[nextRow][nextColumn] != 0) {
                directionIndex = (directionIndex + 1) % 4;  // 顺时针旋转至下一个方向
            }
            row = row + directions[directionIndex][0];
            column = column + directions[directionIndex][1];
        }
        return matrix;
    }
};
posted @ 2021-03-16 10:02  USTC丶ZCC  阅读(43)  评论(0编辑  收藏  举报