DICTIONARY 224ms

Author: profitjean

DEF/DICTIONARY/profitjean.py

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+import sys
+from collections import defaultdict
+input = sys.stdin.readline
+
+def dfs(vertex):
+    global flag
+    visited[vertex] = False
+    adj = graph[vertex]
+    for node in adj:
+        if visited[node] == False:
+            flag = False
+        elif visited[node] == None:
+            dfs(node)
+    sequence.append(vertex)
+    visited[vertex] = True
+
+
+case = int(input().rstrip())
+for _ in range(case):
+    graph = defaultdict(set)
+    N = int(input().rstrip())
+    words = []
+    visited = {}
+    for _ in range(N):
+        words.append(input().rstrip())
+    # 이전 문자열과 비교하면서 다르다면 그래프에 추가시켜주기
+    prev = ""
+    for word in words:
+        for i in range(min(len(prev), len(word))):
+            if prev[i] != word[i]:
+                graph[prev[i]].add(word[i])
+                visited[prev[i]] = None
+                visited[word[i]] = None
+                break
+        prev = word
+    answer = [] #return value
+    for vertex in visited.keys():
+        if visited[vertex] == None:
+            flag = True
+            sequence = []
+            dfs(vertex)
+            if flag:
+                answer.extend(sequence)
+            else:
+                break
+    if flag:
+        alphabet = [a if a not in answer else "" for a in 'abcdefghijklmnopqrstuvwxyz']
+        answer.reverse()
+        answer = "".join(answer+alphabet)
+        print(answer)
+    else:
+        print("INVALID")
+
+