Add C++ solution of problem #2379

Author: Cuda-Chen

2379/solution.cpp

@@ -0,0 +1,25 @@
+// sliding window
+
+class Solution {
+public:
+    int minimumRecolors(string s, int k) {
+        int ans = INT_MAX;
+        int tmp = 0; // store # white blocks
+        auto isWhite = [&](int idx) -> bool {
+            return s[idx] == 'W';
+        };
+
+        for(int i = 0; i < k; i++)
+            tmp += isWhite(i);
+        ans = min(ans, tmp);
+
+        int n = s.size();
+        for(int i = 1; i < n - k + 1; i++) {
+            tmp -= isWhite(i - 1);
+            tmp += isWhite(i + k - 1);
+            ans = min(ans, tmp);
+        }
+
+        return ans;
+    }
+};