【HDOJ6667】Roundgod and Milk Tea（模拟）

题意：有n个班级，每个班级有a[i]个人，b[i]杯奶茶

每个人至多喝一杯奶茶，且不能喝自己班的

问能喝到奶茶的最多总人数

n<=1e6，a[i]，b[i]<=1e9

思路：

做法一：

 #include<bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef pair<int,int> PII;
 typedef pair<ll,ll> Pll;
 typedef vector<int> VI;
 typedef vector<PII> VII;
 //typedef pair<ll,ll>P;
 #define N  1000010
 #define M  200010
 #define fi first
 #define se second
 #define MP make_pair
 #define pb push_back
 #define pi acos(-1)
 #define mem(a,b) memset(a,b,sizeof(a))
 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)
 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)
 #define lowbit(x) x&(-x)
 #define Rand (rand()*(1<<16)+rand())
 #define id(x) ((x)<=B?(x):m-n/(x)+1)
 #define ls p<<1
 #define rs p<<1|1

 const int MOD=1e9+,inv2=(MOD+)/;
       double eps=1e-;
       int INF=1e9;
       int inf=0x7fffffff;
       int dx[]={-,,,};
       int dy[]={,,-,};

 ll a[N],b[N];

 ll read()
 {
    ll v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();
    return v*f;
 }

 void solve()
 {
     int n;
     scanf("%d",&n);
     ll s=,ans=;
     rep(i,,n)
     {
         a[i]=read(),b[i]=read();
         s+=b[i];
     }
     rep(i,,n) ans+=min(a[i],s-b[i]);
     ans=min(ans,s);
     printf("%I64d\n",ans);
 }

 int main()
 {
     int cas=read();
     while(cas--) solve();
     return ;
 }

做法二：题解做法

 #include<bits/stdc++.h>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef pair<int,int> PII;
 typedef pair<ll,ll> Pll;
 typedef vector<int> VI;
 typedef vector<PII> VII;
 #define N  1100000
 #define M  4100000
 #define fi first
 #define se second
 #define MP make_pair
 #define pi acos(-1)
 #define mem(a,b) memset(a,b,sizeof(a))
 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)
 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)
 #define lowbit(x) x&(-x)
 #define Rand (rand()*(1<<16)+rand())
 #define id(x) ((x)<=B?(x):m-n/(x)+1)
 #define ls p<<1
 #define rs p<<1|1

 const ll MOD=1e9+,inv2=(MOD+)/;
       double eps=1e-;
       int INF=1e9;

 int read()
 {
    int v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();
    return v*f;
 }

 int a[N],b[N];

 int main()
 {
     //freopen("1.in","r",stdin);
     int cas;
     scanf("%d",&cas);
     while(cas--)
     {
         int n=read();
         ll sa=,sb=;
         rep(i,,n)
         {
             a[i]=read(); b[i]=read();
             sa+=a[i];
             sb+=b[i];
         }
         if(sa>sb)
         {
             int flag=,s=;
             rep(i,,n)
              if(a[i]+b[i]-(sa-sb)>sb)
              {
                  flag=;
                  s=a[i]+b[i]-(sa-sb)-sb;
              }
              if(flag) printf("%I64d\n",sb-s);
               else printf("%I64d\n",sb);
         }
          else
          {
              int flag=,s=;
              rep(i,,n)
               if(a[i]+b[i]-(sb-sa)>sa)
               {
                  flag=;
                  s=a[i]+b[i]-(sb-sa)-sa;
               }
              if(flag) printf("%I64d\n",sa-s);
               else printf("%I64d\n",sa);
          }
     }

     return ;
 }