HDU 1540 Tunnel Warfare（线段树，单点更新，区间查询）

#include<bits/stdc++.h>
using namespace std;
const int maxn = 50010;
#define lson l , m , num << 1
#define rson m + 1 , r , num << 1|1
int n , m , k , maxo[maxn << 2] , mino[maxn << 2];char s[2];
void up(int num){maxo[num] = max(maxo[num << 1] , maxo[num << 1|1]); mino[num] = min(mino[num << 1] ,mino[num << 1|1]);}
void built(int l , int r , int num){
    if(l == r) {maxo[num] = 0 ; mino[num] = n + 1;return;}
    int m = (l + r)>>1;
    built(lson);built(rson);
    up(num);
    return;
}
void des(int k , int l , int r , int num){
    if(l == r){maxo[num] = k; mino[num] = k;return;}
    int m = (l + r)>>1; if(k <= m) des(k,lson); if(k > m)des(k,rson);up(num);
}
void red(int k , int l , int r , int num){
    if(l == r){maxo[num] = 0; mino[num] = n + 1;return;}
    int m = (l + r)>>1; if(k <= m) red(k,lson); if(k > m)red(k,rson);up(num);
}
int getl(int L , int R , int l , int r , int num){
    if(L <= l && r <= R){return maxo[num];}
    int ans = 0;int m = (l + r) >> 1; if(L <= m) ans = max(ans , getl(L , R , lson));
    if(R > m) ans = max(ans , getl(L , R , rson));
    return ans;
}
int getr(int L , int R , int l , int r , int num){
    if(L <= l && r <= R){return mino[num];}
    int ans = n + 1;int m = (l + r) >> 1; if(L <= m) ans = min(ans , getr(L , R , lson));
    if(R > m) ans = min(ans , getr(L , R , rson));
    return ans;
}
int main()
{
    while(~scanf("%d%d",&n,&m)){
        built(1 , n , 1);
        stack<int>q;
        while(m--){
            scanf("%s",s);
            if(s[0] == ‘D‘){
                 scanf("%d",&k); des(k , 1 , n , 1);
                 q.push(k);
            }
            if(s[0] == ‘R‘){
                if(q.empty()){
                    continue;
                }
                k = q.top(); q.pop();
                red(k , 1 , n , 1);
            }
            if(s[0] == ‘Q‘){
                scanf("%d",&k);
                int ll = getl(1 , k , 1 , n , 1);
                int rr = getr(k , n , 1 , n , 1);
                int ans = rr - ll - 1;
                if(ans < 0) ans = 0;
                printf("%d\n",ans);
            }
        }
    }
}