Merge pull request #246 from H4wk-3yE/patch-2

Create GCD_sum.cpp

Author: probot-auto-merge[bot]

fenwick_tree/GCD_sum.cpp

@@ -0,0 +1,117 @@
+/*
+				C++
+				encoding: UTF-8
+				Modified: <01/Oct/2019 03:02:07 PM>
+
+				✪ H4WK3yE乡
+				Mohd. Farhan Tahir
+				Indian Institute Of Information Technology (IIIT), Gwalior
+*/
+
+#include <bits/stdc++.h>
+#ifdef LOCAL_PROJECT
+#	include <prettypr.hpp>
+#endif
+
+using namespace std;
+
+// clang-format off
+
+#define         ll                     long long
+#define         ve                     vector
+#define         pb                     push_back
+#define         endl                   "\n"
+#define         ff                     first
+#define         ss                     second
+#define         pii                    pair<int, int>
+#define         len(v)                 int(v.size())
+#define         all(v)                 v.begin(), v.end()
+#define         reset(a, b)            memset(a, b, sizeof(a));
+#define         fr(i, s, n)            for (int i = s ; i < n ; ++i)
+#define         dfr(i, s, n)           for (int i = s ; i > n ; --i)
+
+template < typename T > void pr (const T& t) {
+    cout << t << "\n";
+}
+
+template < typename T, typename U, typename... ARGS >
+void pr (const T& t, const U& u, const ARGS&... args) {
+    cout << t << " ";
+    pr (u, args...);
+}
+
+// clang-format on
+#define int long long
+
+const int N = 1e6 + 5;
+int arr[N];
+int bit[N];
+int n;
+const int mod = 1e9 + 7;
+
+int phi[N], F[N];
+void precompute () {
+	fr (i, 1, N) {
+		phi[i] += i;
+		phi[i] %= mod;
+		for (int j = 2 * i; j < N; j += i) {
+			phi[j] -= phi[i];
+			phi[j] = (phi[j] + mod) % mod;
+		}
+	}
+	fr (i, 1, N) {
+		for (int j = i; j < N; j += i) {
+			F[j] += j / i * phi[i];
+			F[j] = (F[j] + mod) % mod;
+			// F[j] %= mod;
+		}
+	}
+}
+
+int query (int x) {
+	int ans = 0;
+	for (; x > 0; x -= (x & (-x))) {
+		ans += bit[x];
+		ans %= mod;
+	}
+	ans = (ans + mod) % mod;
+	// ans %= mod;
+	return ans;
+}
+
+void update (int x, int val, int previous) {
+	for (; x <= n; x += (x & (-x))) {
+		bit[x] -= previous;
+		bit[x] += val;
+		bit[x] %= mod;
+	}
+}
+
+signed main () {
+	ios_base::sync_with_stdio (false), cin.tie (nullptr);
+	precompute ();
+	cin >> n;
+	fr (i, 1, n + 1) cin >> arr[i];
+
+	dfr (i, n, 0) {
+		update (i, F[arr[i]], 0);
+	}
+
+	int tc;
+	cin >> tc;
+	while (tc--) {
+		char t;
+		int x, y;
+		cin >> t >> x >> y;
+		if (t == 'C') {
+			int b = query (y);
+			int a = query (x - 1);
+			pr ((b - a + mod) % mod);
+		} else {
+			int p = F[arr[x]];
+			arr[x] = y;
+			update (x, F[y], p);
+		}
+	}
+	return 0;
+}