题解 | #牛牛的田地#

对角线遍历

#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param mat int整型vector<vector<>> 
     * @return int整型vector
     */
    vector<int> diagonalTraverse(vector<vector<int> >& mat) {
        int n  = mat.size();
        int m = mat[0].size();
        vector<int> ret;
        for(int i=0;i<m+n-1;i++){
            if(i%2==0){
                int r = i < n ? i : n-1;
                int c = i < n ? 0 : i-n+1;
                while(r>=0&&r<n&&c>=0&&c<m) ret.push_back(mat[r--][c++]);
            }
            else {
                int r = i < m? 0 : i-m+1;
                int c = i < m? i : m-1;
                while(r>=0&&r<n&&c>=0&&c<m) ret.push_back(mat[r++][c--]);
            }
        }
        return ret;
    }
};