2017ACM/ICPC广西邀请赛

A.A Math Problem

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
inline ll read(){
    int x=0,f=1;char ch=getchar();
    while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}

/***********************************************************/

const int maxn = 1e5+7;
ll a[maxn];

void init(){
    for(ll i = 1;i <= 15;i++){
        a[i] = 1;
        for(ll j = 1;j <= i;j++){
            a[i] *= i;
        }
        //cout << i << " :" << a[i] << endl;
    }
}


int main(){
    init();
    ll n;
    while(~scanf("%lld", &n)){
        int ans = 0;
        for(ll i = 1;i <= 15;i++){
            if(n >= a[i])
                ans++;
            else break;
        }
        cout << ans << endl;
    }
    return 0;
}

G.Duizi and Shunzi

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
inline ll read(){
    int x=0,f=1;char ch=getchar();
    while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}

/***********************************************************/

const int maxn = 1e6+7;
int a[maxn];

int main(){
    int n;
    while(~scanf("%d", &n)){
        memset(a, 0, sizeof(a));
        for(int i = 1;i <= n;i++){
            int x;
            x = read();
            a[x]++;
        }
        int ans = 0;
        for(int i = 1;i <= n;i++){
            ans += a[i]/2;
            a[i] %= 2;
            if(i+2 <= n){
                if(a[i] && a[i+1]%2 && a[i+2]){
                    ans++;
                    a[i]--;a[i+1]--;a[i+2]--;
                }
            }
            
        }
        printf("%d
", ans);
    }
    return 0;
}