498. Diagonal Traverse

• 题目思路
  题目来源

• C++实现

class Solution
{
public:
    vector<int> findDiagonalOrder(vector<vector<int>>& matrix)
    {
        if(matrix.empty())
        {
            return {};
        }
        vector<int> result;
        bool fromUp = false;  /* false 自下而上 ture 自上而下*/

        int a = 0;
        int b = 0;  //(a,b)  A点

        int c = 0;
        int d = 0;  //(c,d) B点

        int endR = matrix.size() - 1;
        int endC = matrix[0].size() - 1;


        while (a != endR + 1)  //a 走到最后一行的时候b到了最后一列
        {
            this->printLevel(matrix,a,b,c,d,fromUp,result);
            a = (b == endC ? a + 1 : a);
            b = (b == endC ? b : b + 1);
            d = (c == endR ? d + 1 : d);
            c = (c == endR ? c : c + 1);


            fromUp = !fromUp;
        }
        return result;
    }
private:
        /*打印一列*/
    void printLevel(vector<vector<int>>& matrix,int a,int b,int c,int d,bool f,vector<int>& result)
    {
        if (f)
        {
            /*f = true 自上而下的打印矩阵*/
            while (a != c + 1)
            {
                result.push_back(matrix[a][b]);
                a++;
                b--;
            }
        }
        else
        {
            /*f = false 自下而上的打印矩阵*/
            while (c != a - 1)
            {
                result.push_back(matrix[c][d]);
                c--;
                d++;
            }
        }
    }
};