【线段树】 HDOJ 1540 Tunnel Warfare

简单线段树。。。更新的时候就单点更新。。查询的时候就查询x点左右最近的有破坏的点就行了。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 50005
#define maxm 40005
#define eps 1e-10
#define mod 1000000007
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head

int sum[maxn<<2];
char ss[maxn];
stack<int> s;
int ql, qr, n, m, p, v, ans1, ans2;

void pushup(int o)
{
	if(sum[ls] || sum[rs]) sum[o] = 1;
	else sum[o] = 0;
}
void updata(int o, int L, int R)
{
	if(L == R) {
		sum[o] = v;
		return;
	}
	int mid = (L+R)>>1;
	if(p <= mid) updata(lson);
	else updata(rson);
	pushup(o);
}
void query1(int o, int L, int R)
{
	if(ans1) return;
	if(L == R && sum[o]) {
		ans1 = L;
		return;
	}
	int mid = (L+R)>>1;
	if(ql <= L && qr >= R) {
		if(!sum[o]) return;
		if(sum[rs]) query1(rson);
		else query1(lson);
	}
	if(qr > mid) query1(rson);
	if(ql <= mid) query1(lson);
}
void query2(int o, int L, int R)
{
	if(ans2) return;
	if(L == R && sum[o]) {
		ans2 = L;
		return;
	}
	int mid = (L+R)>>1;
	if(ql <= L && qr >= R) {
		if(!sum[o]) return;
		if(sum[ls]) query2(lson);
		else query2(rson);
	}
	if(ql <= mid) query2(lson);
	if(qr > mid) query2(rson);
}
void work(void)
{
	int x;
	while(!s.empty()) s.pop();
	memset(sum, 0, sizeof sum);
	p = 1, v = 1, updata(1, 1, n+2);
	p = n+2, v = 1, updata(1, 1, n+2);
	while(m--) {
		scanf("%s", ss);
		if(ss[0] == 'R') {
			p = s.top(), s.pop(), v = 0;
			updata(1, 1, n+2);
		}
		if(ss[0] == 'D') {
			scanf("%d", &p);
			s.push(++p), v = 1;
			updata(1, 1, n+2);
		}
		if(ss[0] == 'Q') {
			scanf("%d", &x);
			ans1 = ans2 = 0;
			ql = 1, qr = ++x;
			query1(1, 1, n+2);
			ql = x, qr = n+2;
			query2(1, 1, n+2);
			if(ans1 == ans2) printf("0\n");
			else printf("%d\n", ans2 - ans1 - 1);
		}
	}
}
int main(void)
{
	while(scanf("%d%d", &n, &m)!=EOF) work();
	return 0;
}