content
After doing it for three hours, compared with last year, you can do one more dijkstra
In other places, there is no idea at all. I looked at the answers and they are all moving, dfs, bfs, but with my current understanding, it seems that I can't use it.
This time, it's time to experience the topic. In the next two months, the focus will be on returning and searching.
1. Cards
The answer is 3181
hash=[0 for i in range(10)]
i=1
while(i):
string=str(i)
for j in string:
hash[int(j)]+=1
if hash[int(j)]==2021:
print(i)
i=0
break
if i==0:
break
else:i+=12.40257
python decimal arithmetic will be funny
def getline(a,b):
if b[0]-a[0]==0:
k=-1<<31
b=b[0]
else:
k=(b[1]-a[1])/(b[0]-a[0])
b=b[1]-k*b[0]
return (k,b)
point=[]
for i in range(20):
for j in range(21):
point.append((i,j))
ans=[]
for i in range(len(point)):
for j in range(i+1,len(point)):
line=getline(point[i],point[j])
if line not in ans:
ans.append(line)
print(len(ans))3.
4.10266837
def gcd(a,b):
if b==0:
return a
return gcd(b,a%b)
def getmin(a,b):
return a*b//gcd(a,b)
adj=[[]for i in range(2022)]
for i in range(1,2022):
left,right=-1,-1
if i<21:
left=1
right=i+21
elif i>2000:
left=i-21
right=2021
else:
left=i-21
right=i+21
for j in range(left,right+1):
length=getmin(i,j)
adj[i].append((j,length))
d=[1<<31 for i in range(2022)]
vis=[False for i in range(2022)]
def dijkstra():
d[1]=0
for i in range(2021):
minlength=1<<31
minindex=-1
for j in range(1,2022):
if not vis[j] and d[j]<minlength:
minlength=d[j]
minindex=j
if minindex==-1:
return
vis[minindex]=True
for point in adj[minindex]:
index=point[0]
length=point[1]
if not vis[index] and d[index]>d[minindex]+length:
d[index]=d[minindex]+length
dijkstra()
print(d[2021])5.
def gcd(a,b):
if b==0:
return a
return gcd(b,a%b)
adj=[[]for i in range(22)]
for i in range(1,22):
for j in range(i+1,22):
if gcd(i,j)==1:
adj[i].append(j)
adj[j].append(i)
vis=[False for i in range(22)]
ans=0
length=0
def dfs(cur):
global vis
global ans
global length
if 1 in adj[cur] and False not in vis:
ans+=1
return
if False not in vis:
return
for i in adj[cur]:
if not vis[i]:
vis[i]=True
dfs(i)
vis[i]=False
return
# for i in adj:
# print(i)
vis[0]=True
vis[1]=True
dfs(1)
print(ans)6. Time display
a=int(input())
day=24*60*60
s=a//1000
s=s%day
h=s//3600
lst=s%3600
m=lst//60
s=lst%60
print("{:02d}:{:02d}:{:02d}".format(h,m,s))7. Yang Hui Triangle
a=int(input())
dp=[[0 for i in range(a)]for i in range(a)]
dp[0][0]=1
cur=1
def finds():
for i in range(1,a):
dp[i][0]=1
dp[i][i]=1
for j in range(1,i):
dp[i][j]=dp[i-1][j-1]+dp[i-1][j]
if dp[i][j]==a:
cur=(i*(i+1))//2+1+j
return cur
print(finds())