Codeforces Round #354 (Div. 2)-C
High school student Vasya got a string of length n as a birthday present. This string consists of letters 'a' and 'b' only. Vasya denotes beauty of the string as the maximum length of a substring (consecutive subsequence) consisting of equal letters.
Vasya can change no more than k characters of the original string. What is the maximum beauty of the string he can achieve?
The first line of the input contains two integers n and k (1 ≤ n ≤ 100 000, 0 ≤ k ≤ n) — the length of the string and the maximum number of characters to change.
The second line contains the string, consisting of letters 'a' and 'b' only.
Print the only integer — the maximum beauty of the string Vasya can achieve by changing no more than k characters.
4 2
abba
4
8 1
aabaabaa
5
In the first sample, Vasya can obtain both strings "aaaa" and "bbbb".
In the second sample, the optimal answer is obtained with the string "aaaaabaa" or with the string "aabaaaaa".
题意:给定一个长度为n的字符串,字符串只要a和b。现在可以修改k个位置的字符[a->b/ b->a],问包含相同字符的连续子串的长度最长是多少?
思路:滑动窗口。定义L,R下标,当没满足k个修改时,R向右滑,当满足K个时记录最优值然后L向右滑。
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
#include<cstring>
#include<cmath>
#include<bitset>
using namespace std;
#define INF 0x3f3f3f3f
#define PI 3.14159
const int MAXN=+;
char str[MAXN];
int main()
{
#ifdef kirito
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int n,k;
while(~scanf("%d%d",&n,&k)){
scanf("%s",str);
int tota=,totb=;
int L=,R=-,MAXL=-;
while(R+<n)
{
if(min(tota,totb)<=k)
{
R++;
if(str[R]=='a'?tota++:totb++);
if(min(tota,totb)<=k)
{
MAXL=max(MAXL,R-L+);
}
}
else
{
if(str[L]=='a'?tota--:totb--);
L++;
}
}
printf("%d\n",MAXL);
}
return ;
}
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