Merge pull request #512 from Krishna200608/feature/issue-507-salary-queries

Solved Issue #507: Salary Queries (CSES 1144)

Author: Dheeraj-06

Problems/Data-structures/Day-09/sol/Krishna200608/Solution1.cpp

@@ -0,0 +1,140 @@
+/*
+Submission Link:
+https://cses.fi/paste/df31068806cfc4bef186a9/
+*/
+
+/*
+Problem: Salary Queries
+Link: https://cses.fi/problemset/task/1144/
+Author: Krishna200608
+
+Short Problem Statement:
+Maintain an array of salaries. Process queries to update a salary or count employees
+with salaries in a range [a, b]. Values up to 10^9 require coordinate compression.
+
+Approach:
+    Coordinate Compression: Collect all initial salaries and update values.
+    Sort and remove duplicates to map large values to indices.
+    Use a Fenwick Tree (BIT) over compressed indices.
+    Point updates for salary changes.
+    Range queries using prefix sums on BIT.
+
+Time : O(Q log(N+Q))
+Space Complexity: O(N+Q)
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define MOD 1000000007
+const int M = 1e9 + 7;
+const double PI = acos(-1.0);
+#define INF 1e18
+#define pb push_back
+#define ppb pop_back
+#define ll long long
+#define no cout << "NO" << endl
+#define yes cout << "YES" << endl
+#define ff first
+#define ss second
+#define inn(x) int x; cin >> x
+#define ill(x) ll x; cin >> x
+#define all(x) x.begin(), x.end()
+#define in(a) for (int i = 0; i < (int)a.size(); i++) cin >> a[i]
+#define out(a) for (int i = 0; i < (int)a.size(); i++) cout << a[i] << " "
+typedef vector<int> vi;
+typedef vector<ll> vll;
+#define ceil_div(n, x) (((n) % (x) == 0) ? ((n) / (x)) : ((n) / (x) + 1))
+#define debug(x) cout << "x -> " << x << endl
+#define outt(x) cout << x << endl
+#define endl "\n"
+
+const int MAX_M = 600005;
+int bit[MAX_M];
+int max_val;
+
+void update(int idx, int val) {
+    for (; idx <= max_val; idx += idx & -idx)
+        bit[idx] += val;
+}
+
+int query(int idx) {
+    int sum = 0;
+    for (; idx > 0; idx -= idx & -idx)
+        sum += bit[idx];
+    return sum;
+}
+
+void solve() {
+    int n, q;
+    if (!(cin >> n >> q)) return;
+
+    vi p(n);
+    vi vals;
+
+    for (int i = 0; i < n; i++) {
+        cin >> p[i];
+        vals.pb(p[i]);
+    }
+
+    struct Qry {
+        char type;
+        int k, x;
+    };
+
+    vector<Qry> qs(q);
+
+    for (int i = 0; i < q; i++) {
+        cin >> qs[i].type >> qs[i].k >> qs[i].x;
+        if (qs[i].type == '!') vals.pb(qs[i].x);
+    }
+
+    sort(all(vals));
+    vals.erase(unique(all(vals)), vals.end());
+    max_val = vals.size();
+
+    auto get_idx = [&](int v) {
+        return lower_bound(all(vals), v) - vals.begin() + 1;
+    };
+
+    for (int x : p) {
+        update(get_idx(x), 1);
+    }
+
+    for (int i = 0; i < q; i++) {
+        if (qs[i].type == '!') {
+            int k = qs[i].k - 1;
+            int x = qs[i].x;
+            update(get_idx(p[k]), -1);
+            p[k] = x;
+            update(get_idx(x), 1);
+        } else {
+            int a = qs[i].k;
+            int b = qs[i].x;
+
+            int r = upper_bound(all(vals), b) - vals.begin();
+            int l = lower_bound(all(vals), a) - vals.begin();
+
+            outt(query(r) - query(l));
+        }
+    }
+}
+
+signed main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+    cout.tie(nullptr);
+
+    auto begin = chrono::high_resolution_clock::now();
+
+    int t = 1;
+    while (t--) {
+        solve();
+    }
+
+    auto end = chrono::high_resolution_clock::now();
+    auto elapsed = chrono::duration_cast<chrono::nanoseconds>(end - begin);
+    cerr << "Time measured: " << elapsed.count() * 1e-6 << "ms";
+
+    return 0;
+}