Participated in AtCoder Beginner Contest 146

I usually participate in the contest → I end up reviewing it, but I wanted to keep a record of my thoughts during the contest, so I decided to write an article. (I don't know how long it will last)

Problem A --Can't Wait for Holiday

I implemented it honestly.

`A.py`


S = input()

if S == "SUN":
    print(7)
elif S == "MON":
    print(6)
elif S == "TUE":
    print(5)
elif S == "WED":
    print(4)
elif S == "THU":
    print(3)
elif S == "FRI":
    print(2)
else:
    print(1)

Problem B-ROT N

I didn't know how to convert characters to ASCII code, so I asked Google teacher and found out ʻord () and chr () `.

Express the target character as 0 to 25, add N to shift it N times, and divide by 26 to find the remainder. Finally, add ʻord ("A") `to revert to the ASCII code in the uppercase alphabet. The answer was found by doing this for each character.

`B.py`


N = int(input())
S = input()

new_s = []
for c in S:
    new_s.append(chr((ord(c) - ord("A") + N) % 26 + ord("A")))

print("".join(new_s))

Problem C --Buy an Integer

At first I did a full search for N, but it was TLE. (That's right) I thought that PyPy would pass (?), And I repeated TLE. On the way, I realized that a binary search can be used to find the "maximum value among the conditions". I was able to pass it.

It is regrettable that I stuck to one method too much and took 30 minutes to reach the binary search.

`C.py`


a,b,x = map(int, input().split())

left = 0
right = 10**9 + 1
while right > left + 1:
    n = (left + right) // 2
    if a * n + b * len(str(n)) <= x:
        left = n
    else:
        right = n

print(left)

Problem D-Coloring Edges on Tree

It was totally useless. The graph problem gets a rejection reaction the moment I see it, so I want to study hard somewhere, but I haven't touched it ...

Do you have any good learning materials? ??

Summary

I want to turn green soon!

ABC146 Impressions