[USACO5.5]隐藏口令Hidden Password

Posted 2020-08-09 Kurokey

题目链接：传送门

题目大意：给你一个长度 N 的字符串，5<=N<=5,000,000，将首尾合并成环，断环成链并满足字典序最小，输出此时首字母在原串中的位置-1；

题目思路：最小表示法

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <stack>
#include <cctype>
#include <queue>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <climits>
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
#define fi first
#define se second
#define ping(x,y) ((x-y)*(x-y))
#define mst(x,y) memset(x,y,sizeof(x))
#define mcp(x,y) memcpy(x,y,sizeof(y))
using namespace std;
#define gamma 0.5772156649015328606065120
#define MOD 1000000007
#define inf 0x3f3f3f3f
#define N 100005
#define maxn 5000005
typedef pair<int,int> PII;
typedef long long LL;

int n,m,cnt,S,T,k;
char ch[100];
char str[maxn<<1],str1[maxn<<1];

int main(){
    //freopen("in.txt","r",stdin);
    int i,j,Case=0,x,y;
    scanf("%d",&n);
    i=0;
    while(scanf("%s",str+i)!=EOF)i+=72;
    strcpy(str1,str);
    strcat(str,str1);
    i=0,j=1;
    while(i<n&&j<n){
        k=0;
        while(k<n&&str[i+k]==str[j+k])++k;
        if(k==n)break;
        if(str[i+k]>str[j+k])i+=k+1;
        else j+=k+1;
        if(j<=i)j=i+1;
    }
    printf("%d\n",i);
    return 0;
}