cpp: add «525. Contiguous Array»

Signed-off-by: Matej Focko <mfocko@redhat.com>

cpp/contiguous-array.cpp

@@ -0,0 +1,27 @@
+#include <unordered_map>
+#include <vector>
+
+class Solution {
+  public:
+    int findMaxLength(const std::vector<int> &nums) {
+        std::unordered_map<int, int> lengths;
+        lengths[0] = -1;
+
+        int max_length = 0;
+        int count = 0;
+
+        for (auto i = 0u; i < nums.size(); ++i) {
+            count += nums[i] == 1 ? 1 : -1;
+
+            auto len = lengths.find(count);
+            if (len != lengths.end()) {
+                max_length =
+                    std::max(max_length, static_cast<int>(i) - len->second);
+            } else {
+                lengths[count] = i;
+            }
+        }
+
+        return max_length;
+    }
+};