Create shortest-path-in-binary-matrix.cpp

Author: kamyu104

C++/shortest-path-in-binary-matrix.cpp

@@ -0,0 +1,34 @@
+// Time:  O(n^2)
+// Space: O(n)
+
+class Solution {
+public:
+    int shortestPathBinaryMatrix(vector<vector<int>>& grid) {
+        static const vector<pair<int, int>> directions = {{-1, -1}, {-1, 0}, {-1, 1},
+                                                          { 0, -1}, { 0, 1},
+                                                          { 1, -1}, { 1, 0}, { 1, 1}};
+        int result = 0;
+        queue<pair<int, int>> q({{0, 0}});
+        while (!q.empty()) {
+            ++result;
+            queue<pair<int, int>> next_depth;
+            while (!q.empty()) {
+                int i, j;
+                tie(i, j) = q.front(); q.pop();
+                if (0 <= i && i < grid.size() &&
+                    0 <= j && j < grid[0].size() &&
+                    !grid[i][j]) {
+                    grid[i][j] = 1;
+                    if (i == grid.size() - 1 && j == grid.size() - 1) {
+                        return result;
+                    }
+                    for (const auto& dir : directions) {
+                        next_depth.emplace(i + dir.first, j + dir.second);
+                    }
+                }
+            }
+            q = move(next_depth);
+        }
+        return -1;
+    }
+};