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  • LeetCode Spiral Matrix

    class Solution {
        public:
                vector<int> spiralOrder(vector<vector<int> > &matrix) {
                        vector<int> ret;
                        int cols = 0;
                        int rows = 0;
                        if (!(rows = matrix.size()) || !(cols = matrix[0].size())) {
                                return ret;
                        }
                        int left = 0, top = 0, right = cols - 1, bottom = rows - 1;
                        while (left <= right && top <= bottom) {
                            circle_walk(left, top, right, bottom, matrix, ret);
                            left++, top++, bottom--, right--;
                        }
                        return ret;
                }
    
                void circle_walk(int left, int top, int right, int bottom, vector<vector<int> >& map, vector<int>& path) {
                        int rows = 0;
                        if (map.size() < 1 || map[0].size() < 1) return;
                                
                        // top row
                        for (int i=left; i<=right; i++) {
                            path.push_back(map[top][i]);
                        }
    
                        // right col
                        for (int i=top+1; i<=bottom; i++) {
                            path.push_back(map[i][right]);
                        }
    
                        // bottom row
                        for (int i=right-1; bottom != top && i>=left; i--) {
                            path.push_back(map[bottom][i]);
                        }
    
                        // left col
                        for (int i=bottom-1; left != right && i>top; i--) {
                            path.push_back(map[i][left]);
                        }
    
                }
    };

    又隔了好久没有写了,水一发,准备测试数据还是必要的,比如只有一行的matrix,只有一列的matrix等,或许可以发现编码中的问题。

    第二轮:

    Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

    For example,
    Given the following matrix:

    [
     [ 1, 2, 3 ],
     [ 4, 5, 6 ],
     [ 7, 8, 9 ]
    ]
    

    You should return [1,2,3,6,9,8,7,4,5].

    题解简洁很多:

    class Solution {
    public:
        vector<int> spiralOrder(vector<vector<int> > &matrix) {
            vector<int> res;
            
            int m = matrix.size();
            if (m == 0) {
                return res;
            }
            int n = matrix[0].size();
            
            int row = 0, col = -1;
            while(true) {
                for (int i=0; i<n; i++) res.push_back(matrix[row][++col]);
                if (--m == 0) break;
                for (int i=0; i<m; i++) res.push_back(matrix[++row][col]);
                if (--n == 0) break;
                for (int i=0; i<n; i++) res.push_back(matrix[row][--col]);
                if (--m == 0) break;
                for (int i=0; i<m; i++) res.push_back(matrix[--row][col]);
                if (--n == 0) break;
            }
            return res;
        }
    };
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  • 原文地址:https://www.cnblogs.com/lailailai/p/3755088.html
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