2018/2/23 每日一学 后缀数组

int wa[maxn],wb[maxn],wv[maxn],ws[maxn];

int cmp(int *r , int a, int b, int l)
{
    return r[a] == r[b] && r[a+l] == r[b+l];
}
void da (int *r , int *sa , int n, int m)
{
    int i, j, p, *x = wa, *y = wb , *t;
    for(i = 0; i < m; i++) 
        ws[i] = 0;
    for(i = 0; i < n; i++) 
        ws[x[i] = r[i]]++;
    for(i = 1; i < m; i++) 
        ws[i] += ws[i-1];
    for(i = n-1; i >= 0; i--) 
        sa[--ws[x[i]]] = i;
    for(j = 1,p = 1; p < n ; j <<= 1,m = p)
    {
        for(p = 0, i = n - j; i < n; i++) 
            y[p++]=i;
        for(i = 0; i < n; i++)
            if(sa[i] >= j)
                y[p++] = sa[i] - j;
        for(i = 0; i < n; i++)
            wv[i] = x[y[i]];
        for(i = 0; i < m; i++)
            ws[i] = 0;
        for(i = 0; i < n; i++)
            ws[wv[i]]++;
        for(i = 1; i < m; i++)
            ws[i] += ws[i-1];
        for(i = n-1; i >= 0; i--)
            sa[--ws[wv[i]]] = y[i];
        for(t = x,x = y,y = t,p = 1,x[sa[0]] = 0,i = 1; i < n;i++)
            x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
    }
}