Solution Class Reference

Public Member Functions
int	minCost (vector< vector< int > > &grid)

Detailed Description

Definition at line 16 of file main.cpp.

Member Function Documentation

minCost()

int Solution::minCost ( vector< vector< int > > &  grid )

inline

Definition at line 19 of file main.cpp.

    {
        unordered_map<int, pair<int, int>> direction; // direction num, (row, column)
        direction[1] = {0, 1}; 
        direction[2] = {0, -1};
        direction[3] = {1, 0};
        direction[4] = {-1, 0};
 
        int rows = (int)grid.size(), cols = (int)grid[0].size();
        deque<tuple<int, int, int>> q; // (row, column, cost)
        q.push_back({0, 0, 0}); // upper left corner
        
        unordered_map<pair<int, int>, int, pair_hash> min_cost;
        min_cost[{0, 0}] = 0;
 
        while (!q.empty())
        {
            auto [row, col, cost] = q.front();
            q.pop_front();
 
            if (row == rows - 1 && col == cols - 1)
                return cost;
 
            for (auto dir: direction) // dir is a (key, value), where key is 1-4 and value is (row, col)
            {
                auto [d_row, d_col] = dir.second;
                int n_row = d_row + row;
                int n_col = d_col + col;
 
                int n_cost = cost;
                if (dir.first != grid[row][col])
                    n_cost++;
 
                if (n_row < 0 || n_col < 0 || n_row >= rows || n_col >= cols || (min_cost.find({n_row, n_col}) != min_cost.end() && n_cost >= min_cost[{n_row, n_col}]))
                    continue;
 
                min_cost[{n_row, n_col}] = n_cost;
                if (dir.first == grid[row][col])
                    q.push_front({n_row, n_col, n_cost});
                else
                    q.push_back({n_row, n_col, n_cost});
            }
        }
        return min_cost[{rows - 1, cols - 1}];
    }

Referenced by main().

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The documentation for this class was generated from the following file:

• main.cpp