2019百度之星初赛-1

Q1，比最高项，都非零的话，约分即可

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e3+7;
const ll mod = 1e9+7;

int n,m,k;
int ar[maxn], mid[maxn];
int main()
{
    int t;scanf("%d", &t);
    while(t--){
        scanf("%d", &n);
        for(int i=1;i<=n;i++)scanf("%d", ar+i);
        for(int i=1;i<=n;i++)scanf("%d", mid+i);
        int a,b;
        for(int i=n;i>=1;i--){
            if(ar[i]!=0 || mid[i]!=0){
                if(ar[i]==0){
                    a=0;
                    b=1;
                }
                else if(mid[i]==0){
                    a=1;
                    b=0;
                }
                else{
                    a=ar[i];
                    b=mid[i];
                    int c = __gcd(a,b);
                    a/=c;
                    b/=c;
                }
                break;
            }
        }
        printf("%d/%d
",a,b);
    }
    return 0;
}

Q2，维护当前的可取区间即可，两个区间不想交的话，可能会出现最后一步可走一步，可走两步的情况，设置区间范围为2即可

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6+7;
const ll mod = 1e9+7;

int n,m,k;
int ar[maxn], mid[maxn];
int main()
{
    int t;scanf("%d", &t);
    while(t--){
        scanf("%d", &n);
        int x=1,y=int(1e7),ans=0;
        for(int i=1;i<=n;i++){
            int a,b;
            scanf("%d%d",&a,&b);
            int xx = max(x, a);
            int yy = min(y, b);
            if(xx<=yy){
                x=xx;
                y=yy;
            }
            else if(a>y){
                int dis = a-y;
                ans += (dis+1)/2;
                x = a;
                y = a;
                if((dis&1) && (b>a)){
                    y = a+1;
                }
            }
            else if(b<x){
                int dis = x-b;
                ans += (dis+1)/2;
                x = b;
                y = b;
                if((dis&1) && (b>a)){
                    x = b-1;
                }
            }
            else{
                assert(1==2);
            }
        }
        printf("%d
", ans);
    }
    return 0;
}

Q3，代码量巨大，交了一发wa了，还没补题

Q5，找规律喽

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6+7;
const ll mod = 1e9+7;

int main()
{
    ll n;
    int t;scanf("%d", &t);
    while(t--){
        scanf("%I64d", &n);
        if(n&1){
            ll ans;
            if(n%6==3 || n%6==5)ans = n/6;
            else ans = n/6*4+1;
            printf("%I64d
", ans);
        }
        else{
            if(n%6==0 || n%6==2)printf("%I64d
", n/2);
            else{
                printf("%I64d
", n-1);
            }
        }
    }

    return 0;
}