Create 1640.cpp

LeetCode/1640.cpp

@@ -0,0 +1,37 @@
+class Solution {
+public:
+    bool stepSearch(vector<int>& arr, vector<vector<int>>& pieces, vector<bool>& visited, int startIndex) {
+        for (int i = 0; i < pieces.size(); i++)
+        {
+            if (visited[i]) continue;
+            if (pieces[i][0] != arr[startIndex]) continue;
+            if (startIndex + pieces[i].size() > arr.size()) continue;
+
+            // check all elements
+            int j = 1;
+            for (; j < pieces[i].size(); j++) {
+                if (arr[startIndex + j] != pieces[i][j]) break;
+            }
+            if (j != pieces[i].size()) {
+                continue;
+            }
+
+            if (arr.size() == startIndex + pieces[i].size()) return true;
+
+            // step down
+            visited[i] = true;
+            bool ret = stepSearch(arr, pieces, visited, startIndex + pieces[i].size());
+            visited[i] = false;
+
+            if (ret) return true;
+        }
+
+        return false;
+    }
+
+    bool canFormArray(vector<int>& arr, vector<vector<int>>& pieces) {
+        vector<bool> visited(pieces.size(), false);
+
+        return stepSearch(arr, pieces, visited, 0);
+    }
+};