【2020 秋】

a

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int N=1e4+10;
ll a[N],pre[N],suf[N];
ll n;
int main(){

    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        if(i==1) continue;
        if(a[i]>a[i-1])
            pre[i]=pre[i-1]+1;
        else if(a[i]==a[i-1]) pre[i]=pre[i-1];
        else pre[i]=0;
    }
    for(int i=n-1;i>=1;i--){
        if(a[i]>a[i+1]) suf[i]=suf[i+1]+1;
        else if(a[i]==a[i+1]) suf[i]=suf[i+1];
        else suf[i]=0;
    }
	ll ans=2ll*n;
	for(int i=1;i<=n;i++)
		ans+=max(pre[i],suf[i]);
	ans=ans*100ll;
    cout<<ans;
}

b

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
int main(){
    ll n,m; cin>>n>>m;
    vector<ll>a(n);
    for(int i=0;i<n;i++) cin>>a[i];
    int sz=a.size();
    ll ans=0;
    for(int i=0;i<sz;i++){
        ll sum=0;
        for(int j=i;j<sz;j++){
            sum+=a[j];
            if(sum<=m) ans++;
            else break;
        }
    }
    cout<<ans;
}

c

d

#include<bits/stdc++.h>
using namespace std;

typedef pair<int, int> node;
const int N = 1010, M = N * N;
int h[N], d[N], cd[N], e[M], ne[M], w[M], v[M], idx;
int q[N];
int dist[N], sum[N], pre[N];
bool st[N];
int n, m, k;

void add(int a, int b, int p, int q){
    e[idx] = b, w[idx] = p, v[idx] = q, ne[idx] = h[a], h[a] = idx++;
}

// 判断有向图是否有环
bool topsort() {
    int hh = 0, tt = -1;
    for (int i = 0; i < n; i++) if (!d[i]) q[++tt] = i;

    while (hh <= tt) {
        int t = q[hh++];
        for (int i = h[t]; ~i; i = ne[i]){
            int j = e[i];
            d[j]--;
            if (!d[j]) q[++tt] = j;
        }
    }

    if (tt == n - 1) return false;
    return true;
}

void dijkstra(){
    memset(dist, 0x3f, sizeof dist);
    dist[n] = 0, pre[n] = -1;
    priority_queue<node, vector<node>, greater<node>> heap;

    heap.push({ 0, n });

    while (!heap.empty()){
        auto head = heap.top();
        heap.pop();
        int distance = head.first, t = head.second;

        if (st[t]) continue;
        st[t] = true;

        for (int i = h[t]; ~i; i = ne[i]){
            int j = e[i];
            if (dist[j] > distance + w[i]){
                dist[j] = distance + w[i];
                sum[j] = sum[t] + v[i];
                pre[j] = t;
                heap.push({ dist[j], j });
            }
            else if (dist[j] == distance + w[i] && sum[j] < sum[t] + v[i]){
                sum[j] = sum[t] + v[i];
                pre[j] = t;
            }
        }
    }
}

int main(){
    scanf("%d%d", &n, &m);
    memset(h, -1, sizeof h);
    while (m--){
        int a, b, p, q;
        scanf("%d%d%d%d", &a, &b, &p, &q);
        add(a, b, p, q);
        d[b]++;
    }

    // 做完拓扑排序, d已经被清空
    memcpy(cd, d, sizeof d);
    bool circle = topsort();
    if (circle) puts("Impossible.");
    else{
        puts("Okay.");
        // 建立虚拟源点,连向每个起始点
        for (int i = 0; i < n; i++)
            if (!cd[i]) add(n, i, 0, 0);
        dijkstra();
    }
    scanf("%d", &k);
    while (k--){
        int x; scanf("%d", &x);
        if (circle){
            if (!cd[x]) 
                printf("You may take test %d directly.\n", x);
            else puts("Error.");
        }
        else{
            if (!cd[x]) 
                printf("You may take test %d directly.\n", x);
            else{
                vector<int> path;
                for (int i = x; ~pre[i]; i = pre[i]) 
                    path.push_back(i);
                reverse(path.begin(), path.end());
                printf("%d", path[0]);
                for (int i = 1; i < path.size(); i++) 
                    printf("->%d", path[i]);
                puts("");
            }
        }
    }
    return 0;
}