UVA 140 BandWidth

采用的是枚举法，同时在判断的时候注意优化：如果当前计算出来的距离值已经比之前记录的最小距离值大，那么后续的计算就不需要进行了，具体实现见如下代码：

#include<iostream>#include<vector>#include<string>#include<set>#include<stack>#include<queue>#include<map>#include<algorithm>#include<cmath>#include<iomanip>#include<cstring>#include<sstream>#include<cstdio>#include<deque>using namespace std;int main(){string s;while (getline(cin, s)){if (s == "#") break;string s2 = "";for (int i = 0; i < s.size(); i++){if (s[i] != ' ') s2 += s[i];}s = s2;map<char, int> ch2int;map<int, char> int2ch;int amount = 0;for (char start = 'A'; start <= 'Z'; start++){if (s.find(start) != string::npos){ch2int[start] = amount;int2ch[amount] = start;amount++;}}int* result = new int[amount];int* temp = new int[amount];for (int i = 0; i < amount; i++) temp[i] = i;vector<int> head;vector<int> tail;for (int i = 0; i < s.size(); i++){int first = ch2int[s[i]];i += 2;while (i < s.size() && s[i] != ';'){int second = ch2int[s[i]];head.push_back(first);tail.push_back(second);i++;}}int *pos = new int[amount];int ans = 10000000;do{int ans_t = 0;for (int i = 0; i < amount; i++) pos[temp[i]] = i;for (int i = 0; i < head.size(); i++){ans_t = max(ans_t, abs(pos[head[i]] - pos[tail[i]]));if (ans_t >= ans) break;}if (ans_t < ans){ans = ans_t;for (int i = 0; i < amount; i++) result[i] = temp[i];}} while (next_permutation(temp,temp+amount));for (int i = 0; i < amount; i++){cout << int2ch[result[i]] << ' ';}cout << "-> " << ans << endl;}return 0;}