54.Spiral Matrix

思路

• 直接模拟程序运行，设置(rowbegin,rowend,colbegin,colend)变量。注意：要判断是否遍历过。 参考

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector<int> res;
        if(matrix.size() == 0) return {};
        int colbegin = 0,colend = matrix[0].size()-1;
        int rowbegin = 0,rowend = matrix.size()-1;
        while(rowbegin <= rowend && colbegin <= colend){
            for(int i = colbegin; i <= colend; i++){
                res.push_back(matrix[rowbegin][i]);
            }
            rowbegin++;                                         
            //这里也可以加入判断，但实际上没必要
            for(int i = rowbegin; i <= rowend; i++){
                res.push_back(matrix[i][colend]);
            }
            colend--;
            if(rowbegin <= rowend){                             //判断
                for(int i = colend; i >= colbegin; i--){
                    res.push_back(matrix[rowend][i]);
                }
                rowend--;
            }
            if(colbegin <= colend){
                for(int i = rowend; i >= rowbegin; i--){
                    res.push_back(matrix[i][colbegin]);
                }
                colbegin++;
            }
        }
        return res;
    }
};

• dfs：待实现