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#include "leetcode.h"
class Solution {
public:
int shortestPath(vvd(int) & grid, int k) {
int rows = grid.size(), cols = grid[0].size();
int minStep = max(0, rows + cols - 2), obstacles = minStep - 1,
minStepNext = minStep;
if (obstacles <= k)
return minStep;
vvd(int) dirs = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
list<vector<int>> togo;
togo.push_back({0, 0, k});
vector<int> visited(rows * cols, -1);
visited[0] = k;
int steps = 0;
while (togo.size()) {
steps++;
minStep = minStepNext;
for (int i = togo.size(); i > 0; i--) {
int a = togo.front()[0], b = togo.front()[1], c = togo.front()[2];
togo.pop_front();
for (auto &d : dirs) {
int aa = a + d[0], bb = b + d[1];
if (aa < 0 || aa >= rows || bb < 0 || bb >= cols)
continue;
int cc = c - grid[aa][bb];
if (visited[aa * cols + bb] >= cc)
continue;
int stepsToTarget = rows - aa - 1 + cols - bb - 1;
if (stepsToTarget - 1 <= cc && stepsToTarget == minStep - 1)
return steps + stepsToTarget;
togo.push_back({aa, bb, cc});
visited[aa * cols + bb] = cc;
minStepNext = min(minStepNext, stepsToTarget);
}
}
}
return -1;
}
};
int main() {
Solution obj;
vvd(int) grid = {{0, 0, 0}, {1, 1, 0}, {0, 0, 0}, {0, 1, 1}, {0, 0, 0}};
int k = 1;
cout << obj.shortestPath(grid, k);
}
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