题目链接如下：

Online Judge

一个很简洁的写法：UVa 12166 Equilibrium Mobile——思路题_equilibrium mobile uva - 12166-CSDN博客

才33行，真的NB坏了……

我的比较繁琐的代码（能AC），比较之下就能发现，其实不用构建叶子节点的vec，找到一个叶子节点直接把它对应的平衡树算出来就可以了：

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <map>
// #define debugstruct node{long long key;int level;node(long long _key, int _level): key(_key), level(_level){}
};
int T;
std::string ss;
std::vector<node> vec;int main(){#ifdef debugfreopen("0.txt", "r", stdin);freopen("1.txt", "w", stdout);#endifscanf("%d\n", &T);while (T--){getline(std::cin, ss);vec.clear();int level = 0;for (int i = 0; i < ss.size(); ++i){if (ss[i] == '['){level++;} else if (ss[i] == ']'){level--;} else if (ss[i] == ','){continue;} else {vec.push_back(node((long long)std::atoi(ss.substr(i).c_str()), level));while (isdigit(ss[i + 1])){i++;}}}int nbr = 0;std::map<long long, int> mp;for (int i = 0; i < vec.size(); ++i){mp[vec[i].key << vec[i].level]++;}for (auto it = mp.begin(); it != mp.end(); ++it){if (it->second > nbr){nbr = it->second;}}printf("%d\n", vec.size() - nbr);}#ifdef debugfclose(stdin);fclose(stdout);#endifreturn 0;
}

前面还写了两个严重超时的解法，还是贴在下面。

（记录自己的愚蠢。）

超时代码1：

#include <string>
#include <iostream>
#include <cstdlib>
#include <vector>
const int maxx = 99999999;
#define debugstruct node{double key;node* left = nullptr;node* right = nullptr;node* parent = nullptr;
};
int T, cnt;
std::string ss;
std::vector<node*> vec;node* findRoot(std::string str){if (isdigit(str[0])){node* temp = new node;temp->key = (double) std::atoi(str.c_str());vec.push_back(temp);return temp;}str = str.substr(1, str.size() - 2);int nbr = 0;int i;for (i = 0; i < str.size(); ++i){if (str[i] == ',' && nbr == 0){break;}if (str[i] == '['){nbr++;} else if (str[i] == ']'){nbr--;}}node* temp = new node;node* l = findRoot(str.substr(0, i));l->parent = temp;node* r = findRoot(str.substr(i + 1));r->parent = temp;temp->key = l->key + r->key;temp->left = l;temp->right = r;return temp;
}void balance(node* rt, double tot){if (!rt->left && !rt->right){if (rt->key != tot){cnt++;}return;}balance(rt->left, tot / 2);balance(rt->right, tot / 2);
}int main(){#ifdef debugfreopen("0.txt", "r", stdin);freopen("1.txt", "w", stdout);#endifscanf("%d\n", &T);while (T--){vec.clear();getline(std::cin, ss);node* root;root = findRoot(ss);int minn = maxx;for (int i = 0; i < vec.size(); ++i){node* temp = vec[i];while (temp->parent){temp->parent->key = temp->key * 2;temp = temp->parent;}cnt = 0;balance(temp, temp->key);if (cnt < minn){minn = cnt;}}printf("%d\n", minn);}#ifdef debugfclose(stdin);fclose(stdout);#endifreturn 0;
}

超时代码2：

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
const int maxx = 99999999;
#define debugstruct node{long long key;int level;node(long long _key, int _level): key(_key), level(_level){}
};
int T;
std::string ss;
std::vector<node> vec;int main(){#ifdef debugfreopen("0.txt", "r", stdin);freopen("1.txt", "w", stdout);#endifscanf("%d\n", &T);while (T--){getline(std::cin, ss);vec.clear();int level = 0;for (int i = 0; i < ss.size(); ++i){if (ss[i] == '['){level++;} else if (ss[i] == ']'){level--;} else if (ss[i] == ','){continue;} else {vec.push_back(node((long long)std::atoi(ss.substr(i).c_str()), level));while (isdigit(ss[i + 1])){i++;}}}int minn = maxx;for (int i = 0; i < vec.size(); ++i){int cnt = 0;for (int j = 0; j < vec.size(); ++j){if (vec[i].level <= vec[j].level){if (vec[j].key << vec[j].level - vec[i].level != vec[i].key){cnt++;}} else {if (vec[i].key << vec[i].level - vec[j].level != vec[j].key){cnt++;}}}if (cnt < minn){minn = cnt;}}printf("%d\n", minn);}#ifdef debugfclose(stdin);fclose(stdout);#endifreturn 0;
}