Power Calculus UVA - 1374 迭代加深搜索

Posted 2021-01-12 fan-jiaming

迭代加深搜索经典题目，好久不做迭代加深搜索题目，拿来复习了，我们直接对当前深度进行搜索，注意剪枝，还有数组要适当开大，因为2^maxd可能很大

题目：题目链接

AC代码：

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstdlib>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <cstring>
 7 #include <vector>
 8 #include <string>
 9 #include <queue>
10 #include <map>
11 #include <set>
12 
13 #define FRER() freopen("in.txt", "r", stdin);
14 #define INF 0x3f3f3f3f
15 
16 using namespace std;
17 
18 const int maxn = 10000 + 5;
19 
20 int num[maxn], vis[maxn], temp[50], maxd, n;
21 
22 bool dfs(int, int);
23 
24 int main()
25 {
26     //FRER()
27     ios::sync_with_stdio(0);
28     cin.tie(0);
29 
30     temp[0] = 1;
31     for(int i = 1; i < 32; ++ i)
32         temp[i] = temp[i - 1] << 1;
33     while(cin >> n && n) {
34         memset(vis, 0, sizeof(vis));
35         for(maxd = 0; ; ++maxd) 
36             if(dfs(0, 1)) break;
37         cout << maxd << endl;
38     }
39     return 0;
40 }
41 
42 bool dfs(int cur, int s) {
43     if(cur == maxd && s == n) return true;
44     if(cur > maxd) return false;
45     if(s * temp[maxd - cur] < n) return false;
46     num[cur] = s;
47     vis[s] = 1;
48     for(int i = 0; i <= cur; ++i) {
49         int u = num[i] + s;
50         if(!vis[u]) {
51             vis[u] = 1;
52             if(dfs(cur + 1, u)) return true;
53             vis[u] = 0;
54         }
55         u = abs(num[i] - s);
56         if(!vis[u]) {
57             vis[u] = 1;
58             if(dfs(cur + 1, u)) return true;
59             vis[u] = 0;
60         }
61     }
62     vis[s] = 0;
63     return false;
64 }