runtime error: reference binding to misaligned address 0xbebebebebebebec6 for type 'int', which requires 4 byte alignment (stl_vector.h)

Question

i am writing code to solve this problem on leetcode
my strategy to solve this is:

• run dfs for each cell index (x,y)
• on each dfs call check if cell is a destination cell
• accordingly set the flags
• if both flags are true then add this cell to "ans" vector else carry on with the next dfs

class Solution {
public:
    void psUtil(vector<vector<int> >&mat, int x, int y, int m, int n, int &isP, int &isA, vector<vector<int> >&vis, vector<vector<int> >&ans)
    {
        //check dstinations
        if(x == 0 || y == 0)
        {
            isP = 1;
        }
        if(x == m || y == n)
        {
            isA = 1;
        }

        vector<int> cell(2);
        cell[0] = x;
        cell[1] = y;

        // check both dst rched
        if(isA && isP)
        {
            // append to ans
            ans.push_back(cell);
            return;
        }
        // mark vis
        vis.push_back(cell);

        int X[] = {-1, 0, 1, 0};
        int Y[] = {0, 1, 0, -1};
        int x1, y1;

        // check feasible neighbours
        for(int i = 0; i < 4; ++i)
        {
            x1 = x + X[i];
            y1 = y + Y[i];
            if(x1 < 0 || y1 < 0) continue;

            if(mat[x1][y1] <= mat[x][y])
            { 
                vector<vector<int> > :: iterator it;
                vector<int> cell1(2);
                cell1[0] = x1;
                cell1[1] = y1;
                it = find(vis.begin(), vis.end(), cell1);
                if(it == vis.end());
                else continue;
                psUtil(mat, x1, y1, m, n, isP, isA, vis, ans);
                if(isA && isP) return; 
            }
        }
    }
    vector<vector<int>> pacificAtlantic(vector<vector<int>>& matrix) 
    {
        // find dimensions
        int m = matrix.size(); // rows
        int n = matrix[0].size(); // cols
        vector<vector<int> >ans;
        // flags if rched destinations
        int isP, isA;
        isP = isA = 0;
        // iterate for all indices
        for(int x = 0; x < m; ++x)
        {
            for(int y = 0; y < n; ++y)
            {
                // visited nested vector
                vector<vector<int> >vis; 
                psUtil(matrix, x, y, m, n, isP, isA, vis, ans);
                isP = isA = 0;    
            }
        }
        return ans;     
    }
};

and my error on running this is

Runtime Error Message:
Line 924: Char 9: runtime error: reference binding to misaligned address 0xbebebebebebebec6 for type 'int', which requires 4 byte alignment (stl_vector.h)
Last executed input:
[[1,2,2,3,5],[3,2,3,4,4],[2,4,5,3,1],[6,7,1,4,5],[5,1,1,2,4]]

why am i getting this message and how do i fix it?

Answer 1

i found my error ! it was because of a missing boundary check for the newly calculated coordinate and improper boundary check for a coordinate in the beginning of psUtil.

instead of this:

if(x == m || y == n)
.
.
.
if(x1 < 0 || y1 < 0) continue; 

it should be this:

if(x == m-1 || y == n-1)
.
.
.
if(x1 < 0 || y1 < 0 || x1 >= m || y1 >= n) continue;