POJ 3277 - City Horizon

我是用的线段树做的，时间常数好大，感觉拍的不好。本题要注意统计的方式，而且不要省略pushup操作。

 1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4 
 5 #define MAXN 40000
 6 
 7 int _dirty[MAXN * 4 * 4], *const dirty = &_dirty[-1];
 8 
 9 #define recursive_def    int l, int r,int i
10 #define lsi    i<<1
11 #define rsi    lsi | 1
12 #define lsn    l, m, lsi
13 #define rsn    m+1, r, rsi
14 #define pushdown    if (dirty[i] >= 0) {\
15     dirty[lsi] = dirty[rsi] = dirty[i];\
16     dirty[i] = -1;    \
17 }
18 #define pushup        if (dirty[i] < 0 && dirty[lsi] == dirty[rsi]) dirty[i] = dirty[lsi];
19 
20 void update(int L, int R, int h, recursive_def)
21 {
22     if (L<=l && r<=R && dirty[i] >= 0) {
23         if (dirty[i] < h) dirty[i] = h;
24         return;
25     }
26     int m = (l+r) >> 1;
27     pushdown
28     if (L <= m) update(L, R, h, lsn);
29     if (R > m) update(L, R, h, rsn);
30     pushup
31 }
32 
33 int sorted[MAXN*4], sorted_total;
34 
35 int stt_l, stt_r, stt_h;
36 long long rslt;
37 
38 void query0(recursive_def)
39 {
40     if (dirty[i] >= 0) {
41 //        cout << l << ' '<< r << ' ' << dirty[i] << endl;
42         if (dirty[i] == stt_h) stt_r = r;
43         else {
44             rslt += (long long)stt_h * (sorted[stt_r] - sorted[stt_l] + 1);
45             stt_l = l, stt_r = r, stt_h = dirty[i];
46         }
47         return;
48     }
49     int m = (l+r) >> 1;
50     query0(lsn);
51     if (m<r) query0(rsn);
52 }
53 
54 long long query(recursive_def)
55 {
56     rslt = stt_h = 0;
57     query0(l, r, i);
58     rslt += (long long)stt_h *(sorted[stt_r] - sorted[stt_l] + 1);
59     return rslt;
60 }
61 
62 int N;
63 int A[MAXN], B[MAXN], H[MAXN];
64 
65 int main(void)
66 {
67 //    freopen("poj3277.txt", "r", stdin);
68     scanf("%d", &N);
69     sorted_total = 0;
70     for(int i=0; i<N; ++i) {
71         scanf("%d%d%d", &A[i], &B[i], &H[i]);
72         sorted[sorted_total++] = A[i] - 1;
73         sorted[sorted_total++] = A[i];
74         sorted[sorted_total++] = B[i];
75         sorted[sorted_total++] = --B[i];
76     }
77     sort(sorted, sorted + sorted_total);
78     int i, t;
79     i = 0;
80     for(t=1; t<sorted_total; ++t)
81         if (sorted[t-1] != sorted[t])
82             sorted[i++] = sorted[t-1];
83     sorted[i] = sorted[t-1], sorted_total = i+1;
84 
85     dirty[1] = 0;
86     for(int i=0; i<N; ++i) {
87         A[i] = lower_bound(sorted, sorted + sorted_total, A[i]) - sorted;
88         B[i] = lower_bound(sorted, sorted + sorted_total, B[i]) - sorted;
89         update(A[i], B[i], H[i], 0, sorted_total-1, 1);
90     }
91     printf("%lld", query(0, sorted_total-1, 1));
92     return 0;
93 }