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class Solution {
public:
    int rows;
    int cols;
    int minnow;
    int minPathSum(vector<vector<int>> &grid) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        rows = grid.size()-1;
        cols = grid[0].size()-1;

        vector<vector<int>> copygrid(grid.size());
        int sum = 0;
        for(int i = 0; i < grid.size(); i++) {
            for(int j = 0; j < grid[0].size(); j++) {
                sum += grid[i][j];
            }
        }

        for(int i = 0; i < grid.size(); i++) {
            vector<int> tmp(grid[0].size());
            for(int j = 0; j < grid[0].size(); j++) {
                tmp[j] = sum;
            }
            copygrid[i] = tmp;
        }
        copygrid[0][0] = grid[0][0];

        int px[10000], py[10000];
        int cpx[20000], cpy[20000];
        int index = 0;
        px[index]   = 0;
        py[index++] = 0; 
        while(true) {
            int top = index;
            index = 0;
            for(int i = 0; i < top; i++) {
                int x = px[i];
                int y = py[i];
                if(x + 1 <= rows) {
                    if(copygrid[x][y] + grid[x+1][y] < copygrid[x+1][y]) {
                        copygrid[x+1][y] = copygrid[x][y] + grid[x+1][y];
                        cpx[index] = x+1;
                        cpy[index] = y;
                        index++;
                    }
                }
                if(y + 1 <= cols) {
                    if(copygrid[x][y] + grid[x][y+1] < copygrid[x][y+1]) {
                        copygrid[x][y+1] = copygrid[x][y] + grid[x][y+1];
                        cpx[index] = x;
                        cpy[index] = y+1;
                        index++;
                    }
                }
            }
            if(index == 0)
                break;
            for(int i = 0; i < index; i++) {
                px[i] = cpx[i];
                py[i] = cpy[i];
            }
        }
        return copygrid[rows][cols];
    }
};