Given an integer array nums
with possible duplicates, randomly output the index of a given target
number. You can assume that the given target number must exist in the array.
Implement the Solution
class:
-
Solution(int[] nums)
Initializes the object with the arraynums
. -
int pick(int target)
Picks a random indexi
fromnums
wherenums[i] == target
. If there are multiple valid i's, then each index should have an equal probability of returning.
Example 1:
Input
["Solution", "pick", "pick", "pick"]
[[[1, 2, 3, 3, 3]], [3], [1], [3]]
Output
[null, 4, 0, 2]
Explanation
Solution solution = new Solution([1, 2, 3, 3, 3]);
solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning.
solution.pick(1); // It should return 0. Since in the array only nums[0] is equal to 1.
solution.pick(3); // It should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning.
Constraints:
-
1 <= nums.length <= 2 * 104
-
-231 <= nums[i] <= 231 - 1
-
target
is an integer fromnums
. - At most
104
calls will be made topick
.
SOLUTION:
import random
class Solution:
def __init__(self, nums: List[int]):
self.valIndex = {}
for i, num in enumerate(nums):
self.valIndex[num] = self.valIndex.get(num, []) + [i]
def pick(self, target: int) -> int:
return random.choice(self.valIndex[target])
# Your Solution object will be instantiated and called as such:
# obj = Solution(nums)
# param_1 = obj.pick(target)
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