[CF676C]Vasya and String（尺取法，原题）

题目链接：http://codeforces.com/contest/676/problem/C

原题题解链接：http://www.cnblogs.com/vincentX/p/5405468.html

太菜了，昨晚光想着分块，却没考虑做尺取的时候，对于不需要变化的，那对计数器到k不做贡献。早上恍然大悟，5min改出来了…鶸一个。

  1 /*
  2 ━━━━━┒ギリギリ♂ eye！
  3 ┓┏┓┏┓┃キリキリ♂ mind！
  4 ┛┗┛┗┛┃＼○／
  5 ┓┏┓┏┓┃ /
  6 ┛┗┛┗┛┃ノ)
  7 ┓┏┓┏┓┃
  8 ┛┗┛┗┛┃
  9 ┓┏┓┏┓┃
 10 ┛┗┛┗┛┃
 11 ┓┏┓┏┓┃
 12 ┛┗┛┗┛┃
 13 ┓┏┓┏┓┃
 14 ┃┃┃┃┃┃
 15 ┻┻┻┻┻┻
 16 */
 17 #include <algorithm>
 18 #include <iostream>
 19 #include <iomanip>
 20 #include <cstring>
 21 #include <climits>
 22 #include <complex>
 23 #include <fstream>
 24 #include <cassert>
 25 #include <cstdio>
 26 #include <bitset>
 27 #include <vector>
 28 #include <deque>
 29 #include <queue>
 30 #include <stack>
 31 #include <ctime>
 32 #include <set>
 33 #include <map>
 34 #include <cmath>
 35 using namespace std;
 36 #define fr first
 37 #define sc second
 38 #define cl clear
 39 #define BUG puts("here!!!")
 40 #define W(a) while(a--)
 41 #define pb(a) push_back(a)
 42 #define Rint(a) scanf("%d", &a)
 43 #define Rll(a) scanf("%I64d", &a)
 44 #define Rs(a) scanf("%s", a)
 45 #define Cin(a) cin >> a
 46 #define FRead() freopen("in", "r", stdin)
 47 #define FWrite() freopen("out", "w", stdout)
 48 #define Rep(i, len) for(int i = 0; i < (len); i++)
 49 #define For(i, a, len) for(int i = (a); i < (len); i++)
 50 #define Cls(a) memset((a), 0, sizeof(a))
 51 #define Clr(a, x) memset((a), (x), sizeof(a))
 52 #define Full(a) memset((a), 0x7f7f, sizeof(a))
 53 #define pi 3.14159265359
 54 #define RT return
 55 #define lowbit(x) x & (-x)
 56 #define onenum(x) __builtin_popcount(x)
 57 typedef long long LL;
 58 typedef long double LD;
 59 typedef unsigned long long ULL;
 60 typedef pair<int, int> pii;
 61 typedef pair<string, int> psi;
 62 typedef map<string, int> msi;
 63 typedef vector<int> vi;
 64 typedef vector<LL> vl;
 65 typedef vector<vl> vvl;
 66 typedef vector<bool> vb;
 67 
 68 const int maxn = 100010;
 69 int n, k;
 70 int a[maxn];
 71 char s[maxn];
 72 
 73 int main() {
 74     // FRead();
 75     while(~Rint(n) && ~Rint(k)) {
 76         Rs(s+1);
 77         For(i, 1, n+1) {
 78             if(s[i] == 'a') a[i] = 0;
 79             else a[i] = 1;
 80         }
 81         int l = 1, r = 1;
 82         int cur = 0, ans = 0;
 83         while(1) {
 84             if(r > n) break;
 85             while(r <= n && cur <= k) {
 86                 if(a[r] == 0) {
 87                     if(cur == k) break;
 88                     cur++;
 89                 }
 90                 r++;
 91             }
 92             if(r - l > ans) ans = r - l;
 93             while(l <= r && a[l] == 1) l++;
 94             cur--;
 95             l++;
 96         }
 97         int ret = ans;
 98         For(i, 1, n+1) {
 99             if(s[i] == 'a') s[i] = 'b';
100             else s[i] = 'a';
101         }
102         For(i, 1, n+1) {
103             if(s[i] == 'a') a[i] = 0;
104             else a[i] = 1;
105         }
106         l = 1, r = 1; cur = 0, ans = 0;
107         while(1) {
108             if(r > n) break;
109             while(r <= n && cur <= k) {
110                 if(a[r] == 0) {
111                     if(cur == k) break;
112                     cur++;
113                 }
114                 r++;
115             }
116             if(r - l > ans) ans = r - l;
117             while(l <= r && a[l] == 1) l++;
118             cur--;
119             l++;
120         }
121         printf("%d\n", max(ans, ret));
122     }
123     RT 0;
124 }

 

posted @ 2016-05-26 10:49  Kirai  阅读(244)  评论(0)  编辑  收藏  举报