【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 ;

 }