题解 | #玛雅人的密码#
玛雅人的密码
http://www.nowcoder.com/practice/761fc1e2f03742c2aa929c19ba96dbb0
#include<iostream>
#include<cstdio>
#include<queue>
#include<string>
using namespace std;
struct status {
string str;
int time;
status() {}
status(string s, int t) :str(s), time(t) {}
};
string swap(string s, int a, int b) {
string str = s;
str[a] = s[b];
str[b] = s[a];
return str;
}
int BFS(string str) {
queue<status> myQueue;
myQueue.push(status(str, 0));
while (!myQueue.empty()) {
status current = myQueue.front();
myQueue.pop();
if (current.str.find("2012") != string::npos) return current.time;
else {
for (int i = 0; i < str.size() - 1; ++i) myQueue.push(status(swap(current.str, i, i + 1), current.time + 1));
}
}
return -1;
}
int main() {
int n, count_0, count_1, count_2;
string str;
while (cin>>n>>str) {
count_0 = count_1 = count_2 = 0;
for (int i = 0; i < n; ++i) {
if (str[i] == '0')++count_0;
else if (str[i] == '1')++count_1;
else ++count_2;
}
if (count_0 < 1 || count_1 < 1 || count_2 < 2) printf("%d\n", -1);
else {
printf("%d\n", BFS(str));
}
}
return 0;
}