feat: solved day 8 medium

medium/day_8/solution.cpp

@@ -1 +1,38 @@
-//Write your code here
+//Write your code here
+// Code by Jagpreet153
+#include <bits/stdc++.h>
+using namespace std;
+const int P = 131;
+typedef long long ll;
+ll h[10010], p[10010];
+int n;
+string s;
+pair<bool, int> check(int mid) {
+    unordered_map<ll, int> M;
+    for (int i = mid; i <= n; i++) {
+        ll hash = h[i] - h[i - mid] * p[mid];
+        if (M.count(hash)) return make_pair(true, M[hash]);
+        M[hash] = i - mid + 1;
+    }
+    return make_pair(false, -1);
+}
+
+int main() {
+    cin >> s;
+    s = " " + s;
+    n = s.size() - 1;
+    p[0] = 1;
+    for (int i = 1; i <= n; i++) {
+        h[i] = h[i - 1] * P + s[i];
+        p[i] = p[i - 1] * P;
+    }
+    int l = 0, r = n, start = -1;
+    while (l < r) {
+        int mid = (l + r + 1) >> 1;
+        pair<bool, int> result = check(mid);
+        if (result.first) l = mid, start = result.second;
+        else r = mid - 1;
+    }
+    for (int i = start; i < start + l; i++) cout << s[i];
+    return 0;
+}