UVA - 1374 - Power Calculus（迭代加深）

从小到大枚举可能的次数，然后迭代加深搜索验证

#include<cstdio>
#include<cstring>
#include<cctype>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<deque>
#include<queue>
#include<stack>
#include<list>
#include<ctime>
#define all(x) x.begin(), x.end()
typedef long long ll;
typedef unsigned long long llu;
const int MAXN = 1000 + 10;
const int MAXT = 1000 + 10;
const int INF = 0x7f7f7f7f;
const double pi = acos(-1.0);
const double EPS = 1e-6;
using namespace std;

int a[MAXN], ans, n;

bool dfs(int lur){
int pre = a[lur - 1];
if(lur == ans){
if(pre == n) return true;
return false;
}
if((pre << (ans - lur)) < n) return false;
for(int i = 0; i < lur; ++i){
a[lur] = pre + a[i];
if(a[lur] <= 1000 && dfs(lur + 1)) return true;
a[lur] = pre - a[i];
if(a[lur] > 0 && dfs(lur + 1)) return true;
}
return false;
}

int main(){
while(scanf("%d", &n) == 1 && n){
a[0] = 1;
for(ans = 1; !dfs(1); ++ans);
printf("%d\n", ans - 1);
}
return 0;
}