Create spiral-matrix-iii.cpp

kamyu104 · web-flow · commit 32dfcf4881d8 · 2018-08-12T13:42:06.000+08:00
diff --git a/C++/spiral-matrix-iii.cpp b/C++/spiral-matrix-iii.cpp
@@ -0,0 +1,21 @@
+// Time:  O(max(m, n)^2)
+// Space: O(1)
+
+class Solution {
+public:
+    vector<vector<int>> spiralMatrixIII(int R, int C, int r0, int c0) {
+        int r = r0, c = c0;
+        vector<vector<int>> result = {{r, c}};
+        int x = 0, y = 1, i = 0, n = 0;
+        while (result.size() < R * C) {
+            r += x, c += y, ++i;
+            if (0 <= r && r < R && 0 <= c && c < C) {
+                result.push_back({r, c});
+            }
+            if (i == n / 2 + 1) {
+                swap(x, y), y *= -1, ++n, i = 0;
+            }
+        }
+        return result;
+    }
+};
