Runtime error in Python's recursion

I have noticed that whenever I use recursion in Python, even though I get correct output for test cases, I get RE or WA after submission. I changed my code to C++ and used the EXACT SAME logic and it ran just fine. Is there any particular reason as to why this is so?

(I am thinking it might have something to do with recursion limit in python, and hence I changed the recursion limit with sys.setrecursionlimit(n), but to no fruit.)

The problem link is here.

My code in Python:

import sys

def rundfs(v, visited, graph):
    if v not in graph.keys():
        return visited
    for nv in graph[v]:
        if visited[nv] == False:
            visited = rundfs(nv, visited, graph)
    return visited

def find_disjoint_sets(visited, graph):
    dsets = 0
    for v in range(len(visited)):
        if visited[v] == False:
            visited[v] = True
            visited = rundfs(v, visited, graph)
    # print visited
    return dsets

t = int(raw_input())
while t>0:
    flush = raw_input()
    n = int(raw_input())
    s = int(raw_input())
    graph = {}
    for i in range(s):
        v1, v2 = map(int, raw_input().strip().split(' '))

        if v1 in graph.keys():
            graph[v1] = [v2]
        if v2 in graph.keys():
            graph[v2] = [v1]

    visited = [False for i in range(n)]
    print find_disjoint_sets(visited, graph)

Check this if it helps…

Recursion is VERY expensive in python and JAVA. If recursion is deep, then prefer C++ as you get RE:NZEC in python and JAVA due to stack overflow.