Mafia

http://codeforces.com/problemset/problem/348/A

题意：有n个人，在玩一个游戏，游戏表示每局都必须有个管理员参加

告诉你，每个人想当多少局玩家，然后让你求，最少多少局游戏，才能满足题意！

C++版本一

题解：贪心+公式

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
ll ans,cnt,flag,temp,sum;
ll a[N];
char str;
struct node{};
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    //while(t--){
    scanf("%d",&n);
    for(int i=1;i<=n;i++)scanf("%I64d",&a[i]),sum+=a[i],ans=max(a[i],ans);
    n--;
    temp=sum/n;
    if(sum%n)temp++;
    cout<<max(ans,temp)<<endl;
    //}

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}

C++版本二

题解：二分

如果可以进行游戏，那么必定每次游戏都会有一个人当裁判。所以判断是否可以进行游戏的条件就是检查对于n次游戏，是否都有n个人充当裁判。

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=100000+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const ll INF = 0x3f3f3f3f3f3f3f;
int t,n,m,k,p;
ll l,r,u,v;
ll ans,cnt,flag,temp,sum;
ll a[N];
bool sloved(ll num){
    ll cnt=0;
    for(int i=1;i<=n;i++){
        if(num<a[i])return false;
        cnt+=num-a[i];
    }

    return num<=cnt;
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    //while(t--){
    scanf("%d",&n);
    for(int i=1;i<=n;i++)scanf("%I64d",&a[i]);
    l=0;
    r=1e12;
    while(l<=r){
        ll mid=(l+r)>>1;
        if(sloved(mid)){
            ans=mid;
            r=mid-1;
        }else{
            l=mid+1;
        }
    }
    cout<<ans<<endl;
    //}

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}