Create spiral-matrix-iv.cpp

Author: kamyu104

C++/spiral-matrix-iv.cpp

@@ -0,0 +1,22 @@
+// Time:  O(m * n)
+// Space: O(1)
+
+// linked list, array
+class Solution {
+public:
+    vector<vector<int>> spiralMatrix(int m, int n, ListNode* head) {
+        static const vector<pair<int, int>> directions = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+        vector<vector<int>> result(m, vector<int>(n, -1));
+        for (int i = 0, j = 0, d = 0; head; head = head->next) {
+            result[i][j] = head->val;
+            if (!(0 <= i + directions[d].first && i + directions[d].first < m &&
+                  0 <= j + directions[d].second && j + directions[d].second < n &&
+                  result[i + directions[d].first][j + directions[d].second] == -1)) {
+                d = (d + 1) % 4;
+            }
+            i += directions[d].first;
+            j += directions[d].second;
+        }
+        return result;
+    }
+};