Create largest-1-bordered-square.cpp

Author: kamyu104

C++/largest-1-bordered-square.cpp

@@ -0,0 +1,35 @@
+// Time:  O(n^3)
+// Space: O(n^2)
+
+class Solution {
+public:
+    int largest1BorderedSquare(vector<vector<int>>& grid) {
+        auto left(grid), top(grid);
+        for (int i = 0; i < grid.size(); ++i) {
+            for (int j = 0; j < grid[0].size(); ++j) {
+                if (!grid[i][j]) {
+                    continue;
+                }
+                if (i) {
+                    top[i][j] = top[i - 1][j] + 1;
+                }
+                if (j) {
+                    left[i][j] = left[i][j - 1] + 1;
+                }
+            }
+        }
+        for (int l = min(grid.size(), grid[0].size()); l >= 1; --l) {
+            for (int i = 0; i <= grid.size() - l; ++i) {
+                for (int j = 0; j <= grid[0].size() - l; ++j) {
+                    if (min({top[i + l - 1][j],
+                             top[i + l - 1][j + l - 1],
+                             left[i][j + l - 1],
+                             left[i + l - 1][j + l - 1]}) >= l) {
+                        return l * l;
+                    }
+                }
+            }
+        }
+        return 0;
+    }
+};