54. Spiral Matrix

题目

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].

解析

• 自己亲自写才知道很多细节问题：
• bug1:y0==y1写成y0=y1赋值语句
• bug2: for (int row = x1 - 1; row > x0;row--)小标越界row=x1+1
• bug3: 输入为空矩阵判断if ( matrix.empty())后面判断row<=0||col<=0此时已经出现问题了

class Solution_54 {public:    void help(vector
    
     
      >& matrix,vector
      
        &res, int x0, int y0, int x1, int y1)    {        if (x0==x1&&y0==y1)        {            res.push_back(matrix[x0][y0]);        }else if (x0==x1) //最后一行        {            for (int i = y0; i <= y1;i++)            {                res.push_back(matrix[x0][i]);            }        }else if (y1==y0)        {            for (int i = x0; i <= x1;i++)            {                res.push_back(matrix[i][y0]);            }        }        else        {            for (int col = y0; col <= y1;col++)             {                res.push_back(matrix[x0][col]);            }            for (int row = x0 + 1; row <= x1;row++)            {                res.push_back(matrix[row][y1]);            }            for (int col = y1 - 1; col >= y0;col--)            {                res.push_back(matrix[x1][col]);            }            for (int row = x1 - 1; row > x0;row--)            {                res.push_back(matrix[row][y0]);            }        }        return;    }    vector
       
         spiralOrder(vector
        
         
          >& matrix) { vector
          
            res; if ( matrix.empty()) // { return vector
           
            (); //res; } int row = matrix.size(); int col = matrix[0].size(); //后面判断错误：row <= 0 || col <= 0 ，需要计算row,col调用size()出错，需要在函数开始判断 int x0 = 0, y0 = 0, x1 = row - 1, y1 = col - 1; while (x0<=x1&&y0<=y1) { help(matrix,res, x0, y0, x1, y1); x0++; y0++; x1--; y1--; } return res; }};
           
          
         
        
       
      
     
    

题目来源