[51NOD1127]最短的包含字符串（尺取法）

Posted 2020-07-25

题目链接：http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1127

思路：尺取法，一开始我考虑更新右指针，直到遇到一个和l指针指向的字符相同的时候为止，发现这样做ac不了。于是换了一个思路。

一直更新r指针，直到所有字符都出现了一遍后，更新答案和左指针，导致有一个缺口，这时候再更新r指针。

  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("%lld", &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), 0x7f7f7f, sizeof(a))
 53 #define lrt rt << 1
 54 #define rrt rt << 1 | 1
 55 #define pi 3.14159265359
 56 #define RT return
 57 #define lowbit(x) x & (-x)
 58 #define onenum(x) __builtin_popcount(x)
 59 typedef long long LL;
 60 typedef long double LD;
 61 typedef unsigned long long ULL;
 62 typedef pair<int, int> pii;
 63 typedef pair<string, int> psi;
 64 typedef pair<LL, LL> pll;
 65 typedef map<string, int> msi;
 66 typedef vector<int> vi;
 67 typedef vector<LL> vl;
 68 typedef vector<vl> vvl;
 69 typedef vector<bool> vb;
 70 
 71 const int maxn = 100100;
 72 int ascii[256];
 73 char s[maxn];
 74 int n;
 75 
 76 int main() {
 77     // FRead();
 78     while(~Rs(s)) {
 79         Cls(ascii);
 80         n = strlen(s);
 81         if(n < 26) {
 82             printf("No Solution\n");
 83             continue;
 84         }
 85         int ret = 0x7f7f7f;
 86         int cnt = 0;
 87         int l = 0, r = 1;
 88         ascii[s[l]]++; cnt = 1;
 89         while(r < n) {
 90             if(ascii[s[r]] == 0) cnt++;
 91             ascii[s[r]]++;
 92             while(cnt == 26) {
 93                 ret = min(ret, r-l+1);
 94                 ascii[s[l]]--;
 95                 if(ascii[s[l]] == 0) cnt--;
 96                 l++;
 97             }
 98             r++;
 99         }
100         if(ret == 0x7f7f7f) printf("No Solution\n");
101         else printf("%d\n", ret);
102     }
103     RT 0;
104 }