Shopping

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whiteawll 2022-08-16 14:51:17 博主文章分类：练习题目 ©著作权

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// Problem: Shopping
// Contest: NowCoder
// URL: https://ac.nowcoder.com/acm/contest/20960/1037
// Memory Limit: 1048576 MB
// Time Limit: 2000 ms
// 2022-03-04 20:13:26
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;

#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
#define ll long long
#define pii pair<int, int>
#define mset(s,t) memset(s,t,sizeof(t))
#define mcpy(s,t) memcpy(s,t,sizeof(t))
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define mp make_pair

const ll mod = 1e9 + 7;

inline ll qmi (ll a, ll b) {
   ll ans = 1;
   while (b) {
      if (b & 1) ans = ans * a%mod;
      a = a * a %mod;
      b >>= 1;
   }
   return ans;
}
inline int read () {
   int x = 0, f = 0;
   char ch = getchar();
   while (!isdigit(ch)) f |= (ch=='-'),ch= getchar();
   while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
   return f?-x:x;
}
template<typename T> void print(T x) {
   if (x < 0) putchar('-'), x = -x;
   if (x >= 10) print(x/10);
   putchar(x % 10 + '0');
}
inline ll sub (ll a, ll b) {
   return ((a - b ) %mod + mod) %mod;
}
inline ll add (ll a, ll b) {
   return (a + b) %mod;
}
inline ll inv (ll a) {
   return qmi(a, mod - 2);
}
const int N = 1e3 + 10;
int n, m;
vector<int> a, b;
void solve() {
   cin >>  n>> m;
    int f = 0;
    a.clear();
    for (int i = 1; i <= n; i ++) {
        int u, v;
        cin >> u >> v;
        a.pb(u);
        f += v;
    }
    double ans = 0;
   sort(all(a));
   
    for (int i = n - min(f, m); i < n; i ++)
            ans += a[i]*1.0 / 2;
    for (int i = 0; i < n - min(f, m); i ++)
            ans += a[i] ;
    printf("%.1lf\n", ans);
    
}
int main () {
    int t;
    t =1;
    cin >> t;
    while (t --) solve();
    return 0;
}