12166 - Equilibrium Mobile （UVA）

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-优快云博客

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 debug

struct 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 debug
    freopen("0.txt", "r", stdin);
    freopen("1.txt", "w", stdout);
    #endif
    scanf("%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 debug
    fclose(stdin);
    fclose(stdout);
    #endif
    return 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 debug

struct 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 debug
    freopen("0.txt", "r", stdin);
    freopen("1.txt", "w", stdout);
    #endif
    scanf("%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 debug
    fclose(stdin);
    fclose(stdout);
    #endif
    return 0;
}

超时代码2：

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
const int maxx = 99999999;
#define debug

struct 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 debug
    freopen("0.txt", "r", stdin);
    freopen("1.txt", "w", stdout);
    #endif
    scanf("%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 debug
    fclose(stdin);
    fclose(stdout);
    #endif
    return 0;
}