From 641ead1acda087826b52f35884c19e9cf52a9971 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sat, 27 Feb 2021 21:29:07 +0800
Subject: import(solutions): Add leetcode 395.

---
 works/solutions/leetcode/cpp/395.cpp | 56 ++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 works/solutions/leetcode/cpp/395.cpp

(limited to 'works/solutions/leetcode/cpp/395.cpp')

diff --git a/works/solutions/leetcode/cpp/395.cpp b/works/solutions/leetcode/cpp/395.cpp
new file mode 100644
index 0000000..d45eee9
--- /dev/null
+++ b/works/solutions/leetcode/cpp/395.cpp
@@ -0,0 +1,56 @@
+#include <array>
+#include <string>
+
+using std::string;
+
+class Solution {
+public:
+  static int dfs(const std::string &s, int start, int end, int k) {
+    if (end - start < k) {
+      return 0;
+    }
+
+    std::array<int, 26> counts{0};
+
+    for (int i = start; i < end; i++) {
+      counts[s[i] - 'a']++;
+    }
+
+    int max = -1;
+
+    for (char c = 'a'; c <= 'z'; c++) {
+      int count = counts[c - 'a'];
+
+      if (count > 0 && count < k) {
+        int sub_start = start;
+
+        for (int i = start; i < end; i++) {
+          if (s[i] == c) {
+            if (sub_start != i) {
+              max = std::max(dfs(s, sub_start, i, k), max);
+            }
+            sub_start = i + 1;
+          }
+        }
+
+        if (sub_start != end) {
+          max = std::max(dfs(s, sub_start, end, k), max);
+        }
+
+        break; // This is vital.
+      }
+    }
+
+    if (max == -1)
+      return end - start;
+    else
+      return max;
+  }
+
+  int longestSubstring(string s, int k) { return dfs(s, 0, s.size(), k); }
+};
+
+int main() {
+  Solution{}.longestSubstring("aaaaaaaaaaaabcdefghijklmnopqrstuvwzyz", 3);
+  return 0;
+}
-- 
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