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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
  4. #define mofile(s) freopen(s,"r",stdin)
  5. #define outfile(s) freopen(s,"w",stdout)
  6. #define ll long long
  7. #define ii pair<ll,ll>
  8. #define iii pair<ll,ii>
  9. #define fi first
  10. #define se second
  11. #define tf bool
  12. #define ST stack
  13. #define Q deque
  14. #define Q queue
  15. #define S string
  16. #define Ma map
  17. #define UM unormideremid_map
  18. #define SE set
  19. #define str(x) to_string(x)
  20. #define all(a) (a).begin(),(a).end()
  21. #define FOR(i,l,r,mid) for(int i=l;i<=r;i+=mid)
  22. #define FOD(i,l,r,mid) for(int i=r;i>=l;i-=mid)
  23. #define xuong cout<<"\n"
  24. #define midebug(x) cout<<(x)<<" "
  25. #define ppcnt(x) __builtin_popcountll(x)
  26. #define parity(x) __builtin_parityll(x)
  27. #define leamid0(x) __builtin_clzll(x)
  28. #define LOG2 __lg(x)
  29. #define tr0(x) __builtin_ctzll(x)
  30. #define fiset(x) __builtin_ffsll(x)
  31. #define MASK(k) (1LL<<(k))
  32. #define BIT(x,k) ((x)>>(k)&1)
  33. #define pb push_back
  34. #define tron(x) setprecision(x)
  35. #define het return 0
  36. #define base_ 1000000000
  37. template<typename... T>
  38. void in(T&... args) { ((cin >> args), ...); }
  39. template<class X, class Y>
  40.     bool maximize(X &x, const Y &y){return (x < y) ? x = y, 1 : 0;}
  41. template<class X, class Y>
  42.     bool minimize(X &x, const Y &y){return (x > y) ? x = y, 1 : 0;}
  43. const int maxn=1e6+5;
  44. const ll tle=2e8;
  45. const ll INF=1e9+9;
  46. const int base=31;
  47. string bcc="abcmidefghijklmnopqrstuvwxyz";
  48. int midx[]={-1,0,1,0};
  49. int midy[]={0,1,0,-1};
  50. bool sang[10000005];
  51. ll pref[1005][1005],mt[1005][1005];
  52. void sieve(){
  53.     for(int i=1;i<=10000000;++i) sang[i]=1;
  54.     sang[0]=sang[1]=0;
  55.     for(int i=2;i*i<=10000000;++i){
  56.         if(sang[i]){
  57.             for(int j=i*i;j<=10000000;j+=i) sang[j]=0;
  58.         }
  59.     }
  60. }
  61. void lis(){
  62.     vector<int>t;
  63.     vector<int>a;
  64.     int n; cin>>n;
  65.     for(int i=1;i<=n;++i){
  66.         int ai; cin>>ai;
  67.         a.pb(ai);
  68.     }
  69.     for(int x:a){
  70.         auto it=lower_bound(all(t),x);
  71.         if(it==t.end()) t.pb(x);
  72.         else *it=x;
  73.     }
  74. }
  75. void pfs2mid(){
  76.     int n,m,k; cin>>n>>k; m=n;
  77.     for(int i=1;i<=n;++i){
  78.         for(int j=1;j<=m;++j) cin>>mt[i][j];
  79.     }
  80.     for(int i=1;i<=n;++i){
  81.         for(int j=1;j<=m;++j) pref[i][j]=mt[i][j]+pref[i-1][j]+pref[i][j-1]-pref[i-1][j-1];
  82.     }
  83. }
  84. ll qu2mid(int x1,int y1,int x2,int y2){
  85.     return pref[x2][y2]-pref[x1-1][y2]-pref[x2][y1-1]+pref[x1-1][y1-1];
  86. }
  87. void open(){
  88.     if(fopen("mideptrai.INP","r")){
  89.         mofile("mideptrai.INP");
  90.         outfile("mideptrai.OUT");
  91.     }
  92. }
  93. const int MAXN=1e6+5;
  94. const int mod=1e9+7;
  95. inline void add(int &a,int b){
  96.     a+=b;
  97.     if(a >= mod) a-=mod;
  98.     if(a < 0) a+=mod;
  99. }
  100. vector<pair<int,int>> a;
  101. int n,k;
  102. bool check(double mid){
  103.     vector<double> b;
  104.     for(auto [v,w] : a) b.pb(v-mid*w);
  105.     sort(b.rbegin(),b.rend());
  106.     double ans=0;
  107.     for(int i=0;i<k;++i) ans+=b[i];
  108.     return ans>=0;
  109. }
  110. int main(){
  111.     fast;
  112.     in(n,k);
  113.     a.resize(n);
  114.     for(auto &[v,w] : a) in(v,w);
  115.     double l=0,r=1e18;
  116.     for(int i=0;i<100;++i){
  117.         double mid=(l+r)/2.0;
  118.         if(check(mid)) l=mid;
  119.         else r=mid;
  120.     }
  121.     cout<<fixed<<tron(10)<<l;
  122.     het;
  123. }
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
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5 3
1 3
2 2
2 5
4 2
1 4
stdout
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1.0000000000
https://ideone.com/10VGir
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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