Oblique diagonal "zigzag" Matrix Print

Mxn is asked to return a vector <vector <int >> array, the array elements of 0 to mxn -1, requires arranged along oblique lines, as shown below
[0156]
[24710]
[38 911]

class Solution {
public:
    vector<vector<int> > print_rectangle(int m,int n) {
    	
    	vector<vector<int>> ret(m,vector<int>(n));
    	int val = 0;
    	int i = 0;
    	int j = 0;
    	int flag = 0;
    	while(0<=i && i<m && 0<=j && j<n)
    	{
    		if(flag == 0)
    		{
    			while(0<=i && j<n)
    			{
    				ret[i][j] = val;
    				val++;
    				i--; 
    				j++; 
    			}
    			i--; 
    			j++;
    			(j == n-1)?i++:j++;
    		}
    		else
    		{
    			while(i<m && 0<=j)
    			{
    				entitled [i] [j] = val; 
    				val ++; 
    				i ++; 
    				j--; 

    			} 
    			I ++; 
    			j--; 
    			(i == m-1)? j ++ i ++; 
    		} 
    		Flag = 1 flag; 
    	}   	 
    	Return right;        
    } 
};