x = [int(i) for i in input().split()]
n = x[0]
r = x[1]
goal = x[2] * n
exams = []
total = 0
for i in range(n):
a, b = [int(i) for i in input().split()]
total += a
exams.append((b, a))
if total >= goal:
print(0)
else:
exams.sort()
ans = 0 for exam in exams:
avail = r - exam[1]
if avail > 0:
if avail > goal - total:
ans += (goal-total) * exam[0]
break
else:
ans += avail * exam[0]
total += avail
print(ans)
#include <bits/stdc++.h>
#include<unordered_map>
using namespace std;
#define all(v) ((v).begin()), ((v).end())
#define sz(v) (int)v.size()
#define endl "\n"
typedef long long ll;
constexpr auto EPS = 1e-9;
const long long mod = (long long) 1e9 + 7;
const int N = 1e7 + 2;
const double pi = acos(-1);
const int oo = 0x3f3f3f3f;
int dx[] = {1, -1, 0, 0, 1, 1, -1, -1};
int dy[] = {0, 0, 1, -1, 1, -1, 1, -1};
void Fast() {
std::ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
}
int main() {
Fast();
ll n, r, avg;
cin >> n >> r >> avg;
vector<pair<ll, ll>> grades(n);
ll sum = 0;
for (auto &it: grades) {
cin >> it.second >> it.first;
sum += it.second;
}
sort(all(grades));
ll cnt = 0;
ll need = avg * n;
for (int i = 0; i < n; i++) {
if (grades[i].second < r and sum < need) {
if (r - grades[i].second < need - sum) {
cnt += (r - grades[i].second) * grades[i].first;
sum += r - grades[i].second;
} else {
cnt += (need - sum) * grades[i].first;
sum += (need - sum);
}
}
}
cout << cnt << endl;
}1613A - Long Comparison | 1624B - Make AP |
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