HDU1540 Turnal Warfare

线段树保存每个区间的左边最大连续长度和右边最大连续长度~

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string>
using namespace std;
const int maxn=1e6+;
struct node {
    int l,r;
    int ll,rl,ml;
    //左边开始连续的最大长度和右边开始连续的最大长度
    //以及这个区间的最大连续长度
}segTree[maxn*];
void build (int i,int l,int r) {
    segTree[i].l=l;
    segTree[i].r=r;
    segTree[i].ll=segTree[i].rl=segTree[i].ml=r-l+;
    if (l==r) return;
    int mid=(l+r)>>;
    build (i<<,l,mid);
    build (i<<|,mid+,r);
}
void update (int i,int t,int val) {
    if (segTree[i].l==segTree[i].r) {
        if (val==) segTree[i].ll=segTree[i].rl=segTree[i].ml=;
        else segTree[i].ll=segTree[i].rl=segTree[i].ml=;
        return;
    }
    int mid=(segTree[i].l+segTree[i].r)>>;
    if (t<=mid) update (i<<,t,val);
    else update (i<<|,t,val);
    segTree[i].ll=segTree[i<<].ll;
    segTree[i].rl=segTree[i<<|].rl;
    segTree[i].ml=max(segTree[i<<].ml,segTree[i<<|].ml);
    segTree[i].ml=max(segTree[i].ml,segTree[i<<].rl+segTree[i<<|].ll);
    if (segTree[i<<].ll==segTree[i<<].r-segTree[i<<].l+) segTree[i].ll+=segTree[i<<|].ll;
    if (segTree[i<<|].rl==segTree[i<<|].r-segTree[i<<|].l+)
    segTree[i].rl+=segTree[i<<].rl;
}
int query (int i,int t) {
    if (segTree[i].l==segTree[i].r||segTree[i].ml==||segTree[i].ml==segTree[i].r-segTree[i].l+)
    return segTree[i].ml;
    int mid=(segTree[i].l+segTree[i].r)>>;
    if (t<=mid) {
        if (t>=segTree[i<<].r-segTree[i<<].rl+)
        return query (i<<,t)+query (i<<|,mid+);
        else return query (i<<,t);
    }
    else {
        if (t<=segTree[i<<|].l+segTree[i<<|].ll-)
        return query (i<<|,t)+query(i<<,mid);
        else return query (i<<|,t);
    }
}
int a[maxn],top,n,m,x;
string s;
int main () {
    while (~scanf ("%d %d",&n,&m)) {
        build (,,n);
        top=;
        while (m--) {
            cin>>s;
            if (s=="D") {
                scanf ("%d",&x);
                a[top++]=x;
                update (,x,);
            }
            else if (s=="Q") {
                scanf ("%d",&x);
                printf ("%d\n",query(,x));
            }
            else {
                if (x>) {
                    x=a[--top];
                    update (,x,);
                }
            }
        }
    }
    return ;
}