loj2059 「TJOI / HEOI2016」字符串

字符串好难啊不会啊

#include <iostream>
#include <cstdio>
using namespace std;
int n, m, rnk[100005], cnt[100005], tmp[100005], p, mx=128, saa[100005], tot, a, b;
int height[100005], gg[19][100005], mlg[100005], rot[100005], c, d;
char ss[100005];
struct Node{
	int l, r, sum;
}nd[2000005];
void sasort(){
    for(int i=0; i<mx; i++)  cnt[i] = 0;
    for(int i=0; i<n; i++)  cnt[rnk[i]]++;
    for(int i=1; i<mx; i++)  cnt[i] += cnt[i-1];
    for(int i=n-1; i>=0; i--)   saa[--cnt[rnk[tmp[i]]]] = tmp[i];
}
void getSa(){
    for(int i=0; i<n; i++){
        rnk[i] = ss[i];
        tmp[i] = i;
    }
    sasort();
    for(int j=1; p<n; j<<=1){
        p = 0;
        for(int i=n-j; i<n; i++)    tmp[p++] = i;
        for(int i=0; i<n; i++)
            if(saa[i]>=j)
                tmp[p++] = saa[i] - j;
        sasort();
        swap(rnk, tmp);
        p = 1;
        rnk[saa[0]] = 0;
        for(int i=1; i<n; i++)
            if(tmp[saa[i-1]]==tmp[saa[i]] && tmp[saa[i-1]+j]==tmp[saa[i]+j])
                rnk[saa[i]] = p - 1;
            else
                rnk[saa[i]] = p++;
        mx = p;
    }
}
void getHeight(){
	int h=0;
    for(int i=0; i<n; i++){
        if(h)   h--;
        int j=saa[rnk[i]-1];
        while(ss[i+h]==ss[j+h])   h++;
        height[rnk[i]] = h;
    }
}
void getRmq(){
	for(int i=1; i<=n; i++)	gg[0][i] = height[i];
	for(int j=1; j<=17; j++)
		for(int i=1; i<=n; i++){
			if(i+(1<<(j-1))>n)	break;
			gg[j][i] = min(gg[j-1][i], gg[j-1][i+(1<<(j-1))]);
		}
}
int update(int pre, int l, int r, int x){
	int re=++tot;
	nd[re] = nd[pre];
	nd[re].sum++;
	if(l==r)	;
	else{
		int mid=(l+r)>>1;
		if(x<=mid)	nd[re].l = update(nd[pre].l, l, mid, x);
		else	nd[re].r = update(nd[pre].r, mid+1, r, x);
	}
	return re;
}
bool query(int pre, int now, int l, int r, int x, int y){
	if(l>=x && r<=y)	return nd[now].sum-nd[pre].sum>0;
	else{
		int mid=(l+r)>>1;
		bool re=false;
		if(x<=mid)	re |= query(nd[pre].l, nd[now].l, l, mid, x, y);
		if(mid<y)	re |= query(nd[pre].r, nd[now].r, mid+1, r, x, y);
		return re;
	}
}
int main(){
	cin>>n>>m;
	scanf("%s", ss);
	ss[n++] = 0;
	getSa();
	n--;
	getHeight();
	getRmq();
	for(int i=1; i<=n; i++)
		rot[i] = update(rot[i-1], 1, n, rnk[i-1]);
	while(m--){
		scanf("%d %d %d %d", &a, &b, &c, &d);
		int l=1, r=min(b-a+1, d-c+1), mid, re=0;
		while(l<=r){
			mid = (l + r) >> 1;
			int zuo=rnk[c-1], you=rnk[c-1];
			for(int i=17; i>=0; i--)
				if(zuo>=(1<<i) && gg[i][zuo-(1<<i)+1]>=mid)
					zuo -= 1<<i;
			for(int i=17; i>=0; i--)
				if(you+(1<<i)<=n && gg[i][you+1]>=mid)
					you += 1<<i;
			if(query(rot[a-1], rot[b-mid+1], 1, n, zuo, you))
				re = mid, l = mid + 1;
			else
				r = mid - 1;
		}
		printf("%d\n", re);
	}
	return 0;
}