题目：原题链接（中等）
标签：图、并查集、深度优先搜索
| 解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
|---|---|---|---|
| Ans 1 (Python) | O ( Q × N ) O(Q×N) O(Q×N) : 其中N为变量数 | O ( N ) O(N) O(N) | 40ms (62.76%) |
| Ans 2 (Python) | |||
| Ans 3 (Python) |
解法一：
class Solution:
def calcEquation(self, equations: List[List[str]], values: List[float], queries: List[List[str]]) -> List[float]:
params = set(p1 for p1, p2 in equations) | set(p2 for p1, p2 in equations)
size = len(equations)
# 构造图
graph = {param: {} for param in params}
for i in range(size):
(x, y), value = equations[i], values[i]
graph[x][y] = value
graph[y][x] = 1 / value
def dfs(n1, n3, visited, now=1):
for n2 in graph[n1]:
if n2 not in visited:
if n2 == n3:
return now * graph[n1][n2]
else:
v = dfs(n2, n3, visited=visited | {n2}, now=now * graph[n1][n2])
if v != -1:
return v
return -1
# 深度优先搜索解题
ans = []
for x, y in queries:
if x not in graph or y not in graph:
ans.append(-1)
elif x == y:
ans.append(1)
else:
ans.append(dfs(x, y, visited={x}))
return ans
