#AT2215. C - Robot Takahashi
C - Robot Takahashi
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C - Robot Takahashi
Score : $300$ points
Problem Statement
There are $N$ people, each of whom is either a child or an adult. The $i$-th person has a weight of $W_i$.
Whether each person is a child or an adult is specified by a string $S$ of length $N$ consisting of 0
and 1
.
If the $i$-th character of $S$ is 0
, then the $i$-th person is a child; if it is 1
, then the $i$-th person is an adult.
When Takahashi the robot is given a real number $X$,
Takahashi judges a person with a weight less than $X$ to be a child and a person with a weight more than or equal to $X$ to be an adult.
For a real value $X$, let $f(X)$ be the number of people whom Takahashi correctly judges whether they are children or adults.
Find the maximum value of $f(X)$ for all real values of $X$.
Constraints
- $1\leq N\leq 2\times 10^5$
- $S$ is a string of length $N$ consisting of
0
and1
. - $1\leq W_i\leq 10^9$
- $N$ and $W_i$ are integers.
Input
Input is given from Standard Input in the following format:
Output
Print the maximum value of $f(X)$ as an integer in a single line.
5
10101
60 45 30 40 80
4
When Takahashi is given $X=50$, it judges the $2$-nd, $3$-rd, and $4$-th people to be children and the $1$-st and $5$-th to be adults.
In reality, the $2$-nd and $4$-th are children, and the $1$-st, $3$-rd, and $5$-th are adults, so the $1$-st, $2$-nd, $4$-th, and $5$-th people are correctly judged.
Thus, $f(50)=4$.
This is the maximum since there is no $X$ that judges correctly for all $5$ people. Thus, $4$ should be printed.
3
000
1 2 3
3
For example, $X=10$ achieves the maximum value $f(10)=3$.
Note that the people may be all children or all adults.
5
10101
60 50 50 50 60
4
For example, $X=55$ achieves the maximum value $f(55)=4$.
Note that there may be multiple people with the same weight.