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| #include <bits/stdc++.h>
#define R register
#define ll long long
#define sum(a, b, mod) (((a) + (b)) % mod)
#define meow(cat...) fprintf(stderr, cat)
const int MaxN = 4e5 + 10;
const int Max = MaxN << 5;
const int inf = 0x3f3f3f3f;
struct edge
{
int next, to, dis;
} e[Max];
int head[Max], a[MaxN], b[MaxN];
int n, m, cnt, dis[Max], vis[Max], pre[Max];
void add_edge(int u, int v, int d)
{
++cnt;
e[cnt].to = v;
e[cnt].dis = d;
e[cnt].next = head[u];
head[u] = cnt;
};
inline int read()
{
int x = 0;
char ch = getchar();
while (ch > '9' || ch < '0')
ch = getchar();
while (ch <= '9' && ch >= '0')
x = (x << 1) + (x << 3) + (ch ^ 48), ch = getchar();
return x;
}
struct SegmentTree
{
int cnt, idx[Max];
void build(int id, int l, int r)
{
if(l == r)
return (void) (idx[id] = l + n + 1);
idx[id] = ++cnt; int mid = (l + r) >> 1;
build(id << 1, l, mid), build(id << 1 | 1, mid + 1, r);
if(idx[id << 1]) add_edge(idx[id], idx[id << 1], 0);
if(idx[id << 1 | 1]) add_edge(idx[id], idx[id << 1 | 1], 0);
}
void modify(int id, int l, int r, int ql, int qr, int u)
{
if(ql > r || l > qr) return;
if(ql <= l && r <= qr)
return add_edge(u, idx[id], 1);
int mid = (l + r) >> 1;
modify(id << 1, l, mid, ql, qr, u);
modify(id << 1 | 1, mid + 1, r, ql, qr, u);
}
} T;
void bfs()
{
std::deque<int> q;
dis[n] = 0, q.push_back(n);
while(!q.empty())
{
int u = q.front(); q.pop_front();
if(vis[u]) continue; vis[u] = 1;
for(int i = head[u]; i; i = e[i].next)
{
int v = e[i].to;
if(dis[v] > dis[u] + e[i].dis)
{
dis[v] = dis[u] + e[i].dis;
if(!vis[v])
{
if(e[i].dis) q.push_back(v);
else q.push_front(v); pre[v] = u;
}
}
}
}
}
signed main()
{
int now = 0;
n = read(), T.cnt = 2 * n + 1, memset(dis, 0x3f, sizeof(dis));
for(int i = 1; i <= n; i++) a[i] = read();
for(int i = 1; i <= n; i++) b[i] = read();
for(int i = 0; i <= n; i++)
add_edge(i + n + 1, i + b[i], 0);
T.build(1, 0, n);
for(int i = 1; i <= n; i++)
T.modify(1, 0, n, i - a[i], i, i);
bfs(), printf("%d\n", dis[0] == inf ? -1 : dis[0]);
if(dis[0] != inf)
{
std::vector<int> path;
while(now != n)
{
if(n + 1 <= now && now <= 2 * n + 1)
path.push_back(now - n - 1);
now = pre[now];
}
std::reverse(path.begin(), path.end());
for(auto x : path) printf("%d ", x);
}
return 0;
}
|