Merge pull request #247 from H4wk-3yE/patch-3

Create round_numbers.cpp

Author: probot-auto-merge[bot]

fenwick_tree/round_numbers.cpp

@@ -0,0 +1,104 @@
+// https://www.hackerearth.com/practice/data-structures/advanced-data-structures/fenwick-binary-indexed-trees/practice-problems/algorithm/shil-and-round-numbers/
+/*
+				C++
+				encoding: UTF-8
+				Modified: <04/Oct/2019 04:56:19 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         int                    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
+const int N = 2e5 + 5;
+int arr[N], bit[N];
+int n, q;
+
+int rnd (int x) {
+	if (x < 0) return 0;
+	int p = (x % 10);
+	int q;
+	while (x > 0) {
+		q = (x % 10);
+		x /= 10;
+	}
+	return (p == q);
+}
+
+void update (int i, int val) {
+	while (i <= n) {
+		bit[i] += val;
+		i += (i & (-i));
+	}
+}
+
+int query (int i) {
+	int sum = 0;
+	while (i > 0) {
+		sum += bit[i];
+		i -= (i & (-i));
+	}
+	return sum;
+}
+
+signed main () {
+	ios_base::sync_with_stdio (false), cin.tie (nullptr);
+	cin >> n >> q;
+	fr (i, 1, n + 1) {
+		cin >> arr[i];
+		int c = rnd (arr[i]);
+		if (c) update (i, 1);
+	}
+	while (q--) {
+		int t;
+		cin >> t;
+		if (t == 1) {
+			int l, r;
+			cin >> l >> r;
+			int ans = query (r) - query (l - 1);
+			pr (ans);
+		} else {
+			int i, k;
+			cin >> i >> k;
+			if (rnd (arr[i]) and !rnd (k)) {
+				update (i, -1);
+			} else if (!rnd (arr[i]) and rnd (k)) {
+				update (i, 1);
+			}
+			arr[i] = k;
+		}
+	}
+	return 0;
+}