BZOJ 1692: [Usaco2007 Dec]队列变换 后缀数组_贪心

#include <bits/stdc++.h>
#define setIO(s) freopen(s".in", "r", stdin) 
#define maxn 100000
using namespace std;
int n, m, tot; 
int arr[maxn], height[maxn], A[maxn]; 
namespace SA
{
    int rk[maxn], tp[maxn], sa[maxn], tax[maxn]; 
    void qsort()
    {
        for(int i = 0; i <= m ; ++i) tax[i] = 0;
        for(int i = 1; i <= n ; ++i) ++tax[rk[i]]; 
        for(int i = 1; i <= m ; ++i) tax[i] += tax[i - 1];
        for(int i = n; i >= 1 ; --i) sa[tax[rk[tp[i]]]--] = tp[i]; 
    }
    void build()
    {
        for(int i = 1; i <= n ; ++i) rk[i] = arr[i], tp[i] = i;
        qsort(); 
        for(int k = 1; k <= n ; k <<= 1)
        {
            int p = 0;
            for(int i = n - k + 1; i <= n ; ++i) tp[++p] = i; 
            for(int i = 1; i <= n ; ++i) if(sa[i] > k) tp[++p] = sa[i] - k;
            qsort(), swap(rk, tp), rk[sa[1]] = p = 1;
            for(int i = 2; i <= n ; ++i)
            {
                rk[sa[i]] = (tp[sa[i - 1]] == tp[sa[i]] && tp[sa[i - 1] + k] == tp[sa[i] + k]) ? p : ++p; 
            }
            if(n == p) break; 
            m = p; 
        }
        int k = 0;
        for(int i = 1; i <= n ; ++i) rk[sa[i]] = i;
        for(int i = 1; i <= n ; ++i)
        {
            if(k) --k;
            int j = sa[rk[i] - 1]; 
            while(arr[i + k] == arr[j + k]) ++k;
            height[rk[i]] = k; 
        }  
    }
};
int main()
{
    // setIO("input"); 
    int len; 
    char str[2]; 
    scanf("%d",&len);
    for(int i = 1; i <= len; ++i)  scanf("%s", str), arr[++n] = A[i] = (int)(str[0] - ‘A‘); 
    arr[++n] = 0;        
    for(int i = len ; i >= 1 ; --i) arr[++n] = A[i];
    m = 130;  
    SA::build();
    int l = 1, r = len + 2;  
    for(int i = 1; i <= len ; ++i)
    {   
        if(SA::rk[l] < SA::rk[r])
        {
            printf("%c",(char)arr[l] + ‘A‘), ++l; 
        }
        else 
        {
            printf("%c",(char)arr[r] + ‘A‘), ++r;  
        }
        if(i % 80 == 0) printf("\n"); 
    }
    return 0; 
}