【HDOJ】1540 Tunnel Warfare

还不错的一道线段树区间合并。挺巧妙的用法。

  1 /* 1540 */
  2 #include <iostream>
  3 #include <string>
  4 #include <map>
  5 #include <queue>
  6 #include <set>
  7 #include <stack>
  8 #include <vector>
  9 #include <deque>
 10 #include <algorithm>
 11 #include <cstdio>
 12 #include <cmath>
 13 #include <ctime>
 14 #include <cstring>
 15 #include <climits>
 16 #include <cctype>
 17 #include <cassert>
 18 #include <functional>
 19 #include <iterator>
 20 #include <iomanip>
 21 using namespace std;
 22 //#pragma comment(linker,"/STACK:102400000,1024000")
 23
 24 #define sti                set<int>
 25 #define stpii            set<pair<int, int> >
 26 #define mpii            map<int,int>
 27 #define vi                vector<int>
 28 #define pii                pair<int,int>
 29 #define vpii            vector<pair<int,int> >
 30 #define rep(i, a, n)     for (int i=a;i<n;++i)
 31 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 32 #define clr                clear
 33 #define pb                 push_back
 34 #define mp                 make_pair
 35 #define fir                first
 36 #define sec                second
 37 #define all(x)             (x).begin(),(x).end()
 38 #define SZ(x)             ((int)(x).size())
 39 #define lson            l, mid, rt<<1
 40 #define rson            mid+1, r, rt<<1|1
 41
 42 const int maxn = 50005;
 43 int ls[maxn<<2], rs[maxn<<2], ms[maxn<<2];
 44 int S[maxn], top;
 45
 46 void Build(int l, int r, int rt) {
 47     ls[rt] = rs[rt] = ms[rt] = r - l + 1;
 48     if (l == r)
 49         return ;
 50
 51     int mid = (l + r) >> 1;
 52     Build(lson);
 53     Build(rson);
 54 }
 55
 56 void PushUp(int l, int r, int rt) {
 57     int mid = (l + r) >>1;
 58     int lb = rt<<1;
 59     int rb = lb |1;
 60
 61     ls[rt] = ls[lb];
 62     rs[rt] = rs[rb];
 63     if (ls[lb] == mid-l+1)
 64         ls[rt] += ls[rb];
 65     if (rs[rb] == r-mid)
 66         rs[rt] += rs[lb];
 67
 68     ms[rt] = max(ms[lb], ms[rb]);
 69     ms[rt] = max(ms[rt], rs[lb]+ls[rb]);
 70 }
 71
 72 void update(int x, int delta, int l, int r, int rt) {
 73     if (l == r) {
 74         ls[rt] = rs[rt] = ms[rt] = delta;
 75         return ;
 76     }
 77
 78     int mid = (l + r) >> 1;
 79
 80     if (x <= mid) {
 81         update(x, delta, lson);
 82     } else {
 83         update(x, delta, rson);
 84     }
 85
 86     PushUp(l, r, rt);
 87 }
 88
 89 int Query(int x, int l, int r, int rt) {
 90     if (l==r || ms[rt]==0 || ms[rt]==r-l+1)
 91         return ms[rt];
 92
 93     int mid = (l + r) >> 1;
 94     int lb = rt<<1;
 95     int rb = lb |1;
 96
 97     if (x <= mid) {
 98         if (x >= mid-rs[lb]+1) {
 99             return Query(x, lson) + Query(mid+1, rson);
100         } else {
101             return Query(x, lson);
102         }
103     } else {
104         if (x <= mid+ls[rb]) {
105             return Query(mid, lson) + Query(x, rson);
106         } else {
107             return Query(x, rson);
108         }
109     }
110 }
111
112 int main() {
113     ios::sync_with_stdio(false);
114     #ifndef ONLINE_JUDGE
115         freopen("data.in", "r", stdin);
116         freopen("data.out", "w", stdout);
117     #endif
118
119     int n, m, x;
120     char cmd[5];
121     int ans;
122
123     while (scanf("%d %d", &n, &m)!=EOF) {
124         Build(1, n, 1);
125         top = 0;
126         while (m--) {
127             scanf("%s", cmd);
128             if (cmd[0] == ‘D‘) {
129                 scanf("%d", &x);
130                 S[top++] = x;
131                 update(x, 0, 1, n, 1);
132             } else if (cmd[0] == ‘Q‘) {
133                 scanf("%d", &x);
134                 ans = Query(x, 1, n, 1);
135                 printf("%d\n", ans);
136             } else {
137                 if (top > 0) {
138                     x = S[--top];
139                     update(x, 1, 1, n, 1);
140                 }
141             }
142         }
143     }
144
145     #ifndef ONLINE_JUDGE
146         printf("time = %d.\n", (int)clock());
147     #endif
148
149     return 0;
150 }