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
", re);
}
return 0;
}