hiho一下 第二十周（线段树模板）

 1 #include "iostream"
 2 using namespace std;
 3 #define lson l,m,rt<<1
 4 #define rson m+1,r,rt<<1|1
 5 #define bug  cout << "bug!!!" << endl;
 6 const int MAXN = 100010;
 7 
 8 int sum[MAXN<<2];
 9 int p[MAXN<<2];
10 
11 //更新父亲
12 void PushUp(int rt)
13 {
14     sum[rt] = sum[rt<<1] + sum[rt<<1|1];
15 }
16 
17 //下放
18 void PushDown(int rt,int m)
19 {
20     if (p[rt]) {
21         p[rt<<1] = p[rt<<1|1] = p[rt];
22         sum[rt<<1] = (m-(m>>1)) * p[rt];
23         sum[rt<<1|1] = (m >> 1) * p[rt];
24         p[rt] = 0;
25     }
26 }
27 
28 void build(int l,int r, int rt)
29 {
30     if (l == r) {
31         cin >> p[rt];
32         sum[rt] = p[rt];
33         return;
34     }
35     int m = (l+r)>>1;
36     build(lson);
37     build(rson);
38     PushUp(rt);
39 }
40 
41 //区间更新
42 void update(int L,int R,int c,int l,int r,int rt)
43 {
44     if (L <= l && r <= R) {
45         p[rt] = c;
46         sum[rt] = c*(r-l+1);
47         return;
48     }
49     PushDown(rt,r-l+1);
50     int m = (l+r)>>1;
51     if (L <= m) update(L,R,c,lson);
52     if (R >  m) update(L,R,c,rson);
53     PushUp(rt);
54 }
55 
56 //区间查询
57 int query(int L, int R,int l,int r,int rt)
58 {
59     if(L <= l && R >= r) {
60         return sum[rt];
61     }
62     PushDown(rt,r-l+1);//比如rt存的1-4的和 而查询2-5 1-4就需要下放
63     int m = (l + r) >> 1;
64     int re = 0;
65     if (L <= m) re += query(L,R,lson);
66     if (R >  m) re += query(L,R,rson);
67     return re;
68 }
69 
70 int main()
71 {
72     int n;
73     cin >> n;
74     build(1,n,1);
75     int t;
76     cin >> t;
77     for (int i = 0;i < t;++ i) {
78         int ok;
79         cin >> ok;
80         if (ok) {
81             int p1,p2,c;
82             cin >> p1 >> p2 >> c;
83             update(p1,p2,c,1,n,1);
84         }
85         else {
86             int p1,p2;
87             cin >> p1 >> p2;
88             cout << query(p1,p2,1,n,1) << endl;
89         }
90     }
91 }