- Combination:
都是i从s开始，而Permutation都是i从0开始
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| nums = [...]
ans = []
# C(m, n)
func dfs(n, s, cur):
if cur.size() == n:
ans.append(cur)
return
for i = s to nums.size():
cur.append(nums[i])
dfs(n, i + 1, cur)
cur.pop()
for i = 0 to nums.size():
dfs(i, 0, [])
|
- Permutation:
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| nums = [...]
ans = []
used = [False] * nums.size()
# P(m, n)
func dfs(n, s, cur):
if cur.size() == n:
ans.append(cur)
return
for i = 0 to nums.size():
if used[i]: continue
used[i] = True
cur.append(nums[i])
dfs(n, i + 1, cur)
cur.pop()
used[i] = False
for i = 0 to nums.size():
dfs(i, 0, [])
|