sicily 1768

//如果队列inSeq中存在i<j<k，使得inSeq[k]<inSeq[i]<inSeq[j]，那么inSeq[i]和inSeq[j]不能被放进同一个栈中#include <iostream>#include <stack>#include <cmath>#include <cstring>#include <string>using namespace std;#define INF 10000int color[1010];bool adj[1010][1010];int _min[1010];int n;int inSeq[1010];stack<int> s1;stack<int> s2;string path;bool dfs(int cur) {for(int i = 0; i < n; i++) {if(adj[cur][i]) {if(color[i] == 0) {color[i] = 3 - color[cur];if(!dfs(i)) return false;}else if(color[i] == color[cur]) return false;}}return true;}int main() {//freopen("1.txt", "r", stdin);while(cin >> n) {for(int i = 0; i < n; i++)cin >> inSeq[i];_min[n] = INF;memset(adj, false, sizeof(adj));memset(color, 0, sizeof(color));for(int i = n - 1; i >= 0; i--)_min[i] = min(inSeq[i], _min[i + 1]);//找到所有无向边for(int i = 0; i < n; i++) {for(int j = i + 1; j < n; j++) {if(inSeq[i] < inSeq[j] && inSeq[i] > _min[j + 1]) {adj[i][j] = adj[j][i] = true;}}}//染色bool ok = true;for(int i = 0; i < n; i++) {if(color[i] == 0) {color[i] = 1;if(!dfs(i)) {ok = false;break;}}}if(!ok) {cout << 0 << endl;continue;}//模拟求解int out = 0;//输出队列的元素个数path = "";for(int i = 0; i < n; i++) {if(color[i] == 1) {path += "a ";s1.push(inSeq[i]);}else {path += "c ";s2.push(inSeq[i]);}while((!s1.empty() && s1.top() == out + 1) || (!s2.empty() && s2.top() == out + 1)) {if(s1.top() == out + 1) {path += "b ";s1.pop();}else {path += "d ";s2.pop();}out++;}}path.erase(path.size() - 1, 1);cout << path << endl;}return 0;}