湖南大学第十五届程序设计竞赛

B Kuangyeye’s Resistance

这题需要一定的物理知识，将电阻串并联的关系理清，在加一个递推式即可。

#include<bits/stdc++.h>
using namespace std;
#define maxn 100005
#define ll long long
 
ll n,R,p;
ll a[maxn],b[maxn];
ll poww(ll a,ll b){
    ll ans=1,base=a%p;
    while(b!=0){
        if(b&1!=0)ans=(ans*base)%p;
        base=(base*base)%p;
        b>>=1;
    }
    return ans%p;
}
 
int main()
{
    scanf("%lld %lld %lld",&n,&R,&p);
    a[1]=1,b[1]=1;
    for(int i=2;i<=n;i++)
        a[i]=(2+a[i-1])*poww(3+a[i-1],p-2)%p;
    printf("%lld
",a[n]*R%p);
    return 0;
}

C One Piece

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int maxn = 1e5+7;
ll t,n;
ll lowbit(ll x){
    return (-x) & x;
}
int main(){
    int t ;
    scanf("%lld", &t) ;
    while(t--){
        scanf("%lld", &n);
        int cnt = 0;
        if(n < 0) n += (1ll<<32);
        for(ll i = n ; i > 0 ; i -= lowbit(i)) cnt ++;
        cout << cnt << endl;
    }
    return 0;
}

D Kth height

这题主要是二分套二分这个思路不好想，找出两个队伍中第k矮的。

#include<bits/stdc++.h>
using namespace std;
#define maxn 300005
#define ll long long
 
int n,m;
int s1[maxn],s2[maxn];
int a,b,c,d;
int main()
{
    while(~scanf("%d",&n)){
        for(int i=1;i<=n;i++)
            scanf("%d",&s1[i]);
        for(int i=1;i<=n;i++)
            scanf("%d",&s2[i]);
        scanf("%d",&m);
        while(m--){
            scanf("%d %d %d %d",&a,&b,&c,&d);
            if(a==1)s1[b]=c;
            else s2[b]=c;
            int l=0,r=d,ans;
            while(l<=r){
                int mid=(l+r)/2;
                int t=upper_bound(s2+1,s2+n+1,s1[mid])-s2-1;
                if(mid+t<=d){
                    l=mid+1;
                    ans=mid;
                }
                else if(mid+t>d)r=mid-1;
            }
            int maxx=max(s1[ans],s2[d-ans]);
            printf("%d
",maxx);
        }
    }
    return 0;
}

F Cards with Numbers

这题虽然看上去简单，但是由于数据的缘故，空间和时间的复杂度要求比较高，自然就不能用常规方法来解，这里我们对数据进行离线处理，二分一下就ok了。

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
#define ull unsigned long long
#define endl '
'
const double pi = acos(-1);
const int maxn = 1e6 + 10;
const int maxm = 2e7 + 10;
const ll mod = 998244353;
int t, tt, n, m, op;
struct node{
    int x;
    int y;
}a[maxn], b[maxn];
bool cmp(node aa, node bb){
    return aa.x < bb.x;
}
int main(){
    scanf("%d", &n);
    for(int i = 1 ; i <= n ; ++ i){
        scanf("%d %d", &op, &m);
        if(op == 0) a[++t].x = m, a[t].y=i;
        if(op == 1) b[++tt].x = m, b[tt].y=i;
    }
    sort(a + 1, a + 1 + t, cmp);
    for(int i = 1 ; i <= tt ; ++ i){
        int l = 1, r = t;
        while(l <= r){
            int mid = (l + r) >> 1;
            if(a[mid].x==b[i].x){
                l = mid;break;
            }
            else if(a[mid].x < b[i].x) l = mid + 1;
            else r = mid - 1;
        }
        int p = l;
        if(a[p].x==b[i].x&&a[p].y<b[i].y) cout << "yes" <<endl;
        else cout << "no" <<endl;
    }
    return 0;
}

G Longest Palindrome Substring

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
#define ull unsigned long long
#define endl '
'
const double pi = acos(-1);
const int maxn = 1e5 + 10;
const int maxm = 2e7 + 10;
const ll mod = 998244353;
int n, flag;
char s[maxn];
int main(){
    scanf("%d", &n);
    scanf("%s", s);
    int len = strlen(s);
    for(int i = 1 ; i < len ; ++ i){
        if(s[i]==s[i-1]){
            flag = 1;
            break;
        }
    }
    for(int i = 1 ; i < len - 1 ; ++ i){
        if(s[i+1]==s[i-1]){
            flag = 1;
            break;
        }
    }
    if(flag) cout << "YES";
    else cout << "NO";
    return 0;
}

I Algorithm Choosing Mushrooms

贪心

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
#define ull unsigned long long
#define endl '
'
const double pi = acos(-1);
const int maxn = 2e5 + 10;
const int maxm = 2e7 + 10;
const ll mod = 998244353;
int n, m;
ll a[maxn], m1, m2, p[maxn];
struct node{
    ll sum, id;
}s[maxn];
bool cmp(node a, node b){
    return a.sum == b.sum ? a.id < b.id : a.sum < b.sum;
}
int main(){
    scanf("%d %d", &n, &m);
    for(int i = 1 ; i <= n ; ++ i){
        scanf("%d", &a[i]);
        s[i].sum = (s[i-1].sum + a[i]) % m;
        p[i] = p[i-1]+a[i];
        s[i].id = i;
    }
    //for(int i = 1 ; i <= n ; ++ i) cout << s[i].sss << ' ';
    //cout << endl;
    sort(s + 1, s + 1 + n, cmp);
 
    int t = 1;
    for(int i = 1 ; i <= n ; ++ i){
        if(s[i].sum!=s[t].sum){
            int r = s[i-1].id, l = s[t].id;
            //cout << l << ' ' << r << endl;
            m1 = max(p[r]-p[l], m1);
            //cout << s[r].sss-s[l].sss << endl;
            m2 = max(m2, (ll)(r-l));
            t = i;
        }
    }
    //cout << t << endl;
    //cout << s[t-1].sss << ' ' << s[n].sss << endl;
    int r = s[n].id, l = s[t].id;
    m1 = max(p[r]-p[l], m1);
    m2 = max(m2, (ll)(r-l));
 
    cout << m1 << ' ' << m2;
    return 0;
}