Create Spiral.cpp

Cpp/Spiral.cpp

@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<int> spiralOrder(vector<vector<int> >& matrix)
+{
+    int m = matrix.size(), n = matrix[0].size();
+    vector<int> ans;
+
+    if (m == 0)
+        return ans;
+
+    vector<vector<bool> > seen(m, vector<bool>(n, false));
+    int dr[] = { 0, 1, 0, -1 };
+    int dc[] = { 1, 0, -1, 0 };
+
+    int x = 0, y = 0, di = 0;
+
+    // Iterate from 0 to m * n - 1
+    for (int i = 0; i < m * n; i++) {
+        ans.push_back(matrix[x][y]);
+        // on normal geeksforgeeks ui page it is showing
+        // 'ans.push_back(matrix[x])' which gets copied as
+        // this only and gives error on compilation,
+        seen[x][y] = true;
+        int newX = x + dr[di];
+        int newY = y + dc[di];
+
+        if (0 <= newX && newX < m && 0 <= newY && newY < n
+            && !seen[newX][newY]) {
+            x = newX;
+            y = newY;
+        }
+        else {
+            di = (di + 1) % 4;
+            x += dr[di];
+            y += dc[di];
+        }
+    }
+    return ans;
+}
+
+// Driver code
+int main()
+{
+    vector<vector<int> > a{ { 1, 2, 3, 4 },
+                            { 5, 6, 7, 8 },
+                            { 9, 10, 11, 12 },
+                            { 13, 14, 15, 16 } };
+
+    // Function call
+    for (int x : spiralOrder(a)) {
+        cout << x << " ";
+    }
+    return 0;
+}