线段树

线段树（单点修改）

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 struct node {
 5     int start, end;
 6     int val;
 7     node *left, *right;
 8     node(int _start, int _end) :
 9         start(_start), end(_end), val(INT_MAX), left(NULL), right(NULL) {}
10 };
11 
12 node *buildTree(int start, int end) {
13     if (start > end) return NULL;
14     node *root = new node(start, end);
15     if (start == end) return root;
16     int mid = start + ((end - start) >> 1);
17     root->left = buildTree(start, mid);
18     root->right = buildTree(mid + 1, end);
19     return root;
20 }
21 
22 void update(node *root, int idx, int val) {
23     if (idx == root->start && idx == root->end) {
24         root->val = val;
25         return;
26     }
27     int mid = root->start + ((root->end - root->start) >> 1);
28     if (idx >= root->start && idx <= mid) update(root->left, idx, val);
29     else if (idx > mid && idx <= root->end) update(root->right, idx, val);
30     root->val = min(root->left->val, root->right->val);
31 }
32 
33 int query(node *root, int start, int end) {
34     if (start == root->start && end == root->end) return root->val;
35     int mid = root->start + ((root->end - root->start) >> 1);
36     if (end <= mid) return query(root->left, start, end);
37     if (start > mid) return query(root->right, start, end);
38     return min(query(root->left, start, mid), query(root->right, mid + 1, end));
39 }
40 
41 int N, Q;
42 int idx, val;
43 int op;
44 
45 int main() {
46     cin >> N;
47     node *root = buildTree(1, N);
48     for (idx = 1; idx <= N; ++idx) {
49         cin >> val;
50         update(root, idx, val);
51     }
52     cin >> Q;
53     for (int i = 0; i < Q; ++i) {
54         cin >> op >> idx >> val;
55         if (op == 0) cout << query(root, idx, val) << endl;
56         else update(root, idx, val);
57     }
58     return 0;
59 }

线段树（区间修改）

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 struct node {
 5     int start, end;
 6     int val;
 7     int tag;
 8     node *left, *right;
 9     node(int _start, int _end) :
10         start(_start), end(_end), val(0), tag(-1),
11         left(NULL), right(NULL) {}
12 };
13 
14 node *buildTree(int start, int end) {
15     if (start > end) return NULL;
16     node *root = new node(start, end);
17     if (start == end) return root;
18     int mid = start + ((end - start) >> 1);
19     root->left = buildTree(start, mid);
20     root->right = buildTree(mid + 1, end);
21     return root;
22 }
23 
24 void update(node *root, int start, int end, int val) {
25     if (start == root->start && end == root->end) {
26         root->tag = val;
27         root->val = val * (end - start + 1);
28         return;
29     }
30     int mid = root->start + ((root->end - root->start) >> 1);
31     if (root->tag != -1) {
32         root->left->tag = root->tag;
33         root->left->val = root->tag * (root->left->end - root->left->start + 1);
34         root->right->tag = root->tag;
35         root->right->val = root->tag * (root->right->end - root->right->start + 1);
36         root->tag = -1;
37     }
38     if (end <= mid) update(root->left, start, end, val);
39     else if (start > mid) update(root->right, start, end, val);
40     else update(root->left, start, mid, val), update(root->right, mid + 1, end, val);
41     root->val = root->left->val +  root->right->val;
42 }
43 
44 int query(node *root, int start, int end) {
45     if (start == root->start && end == root->end) return root->val;
46     if (root->tag != -1) {
47         root->left->tag = root->tag;
48         root->left->val = root->tag * (root->left->end - root->left->start + 1);
49         root->right->tag = root->tag;
50         root->right->val = root->tag * (root->right->end - root->right->start + 1);
51         root->tag = -1;
52     }
53     int mid = root->start + ((root->end - root->start) >> 1);
54     if (end <= mid) return query(root->left, start, end);
55     if (start > mid) return query(root->right, start, end);
56     return query(root->left, start, mid) + query(root->right, mid + 1, end);
57 }
58 
59 int N, Q;
60 int idx, val, st, ed;
61 int op;
62 
63 int main() {
64     cin >> N;
65     node *root = buildTree(1, N);
66     for (idx = 1; idx <= N; ++idx) {
67         cin >> val;
68         update(root, idx, idx,  val);
69     }
70     cin >> Q;
71     for (int i = 0; i < Q; ++i) {
72         cin >> op >> st >> ed;
73         if (op == 0) {
74             cout << query(root, st, ed) << endl;
75         } else {
76             cin >> val;
77             update(root, st, ed, val);
78         }
79     }
80     return 0;
81 }

 

posted @ 2015-06-14 18:48  Eason Liu  阅读(115)  评论(0)    收藏  举报