1326. Minimum Number of Taps to Open to Water a Garden
https://leetcode.com/problems/minimum-number-of-taps-to-open-to-water-a-garden
Description
There is a one-dimensional garden on the x-axis. The garden starts at the point 0
and ends at the point n
. (i.e The length of the garden is n
).
There are n + 1
taps located at points [0, 1, ..., n]
in the garden.
Given an integer n
and an integer array ranges
of length n + 1
where ranges[i]
(0-indexed) means the i-th
tap can water the area [i - ranges[i], i + ranges[i]]
if it was open.
Return the minimum number of taps that should be open to water the whole garden, If the garden cannot be watered return -1.
Example 1:

**Input:** n = 5, ranges = [3,4,1,1,0,0]
**Output:** 1
**Explanation:** The tap at point 0 can cover the interval [-3,3]
The tap at point 1 can cover the interval [-3,5]
The tap at point 2 can cover the interval [1,3]
The tap at point 3 can cover the interval [2,4]
The tap at point 4 can cover the interval [4,4]
The tap at point 5 can cover the interval [5,5]
Opening Only the second tap will water the whole garden [0,5]
Example 2:
**Input:** n = 3, ranges = [0,0,0,0]
**Output:** -1
**Explanation:** Even if you activate all the four taps you cannot water the whole garden.
Example 3:
**Input:** n = 7, ranges = [1,2,1,0,2,1,0,1]
**Output:** 3
Example 4:
**Input:** n = 8, ranges = [4,0,0,0,0,0,0,0,4]
**Output:** 2
Example 5:
**Input:** n = 8, ranges = [4,0,0,0,4,0,0,0,4]
**Output:** 1
Constraints:
1 <= n <= 104
ranges.length == n + 1
0 <= ranges[i] <= 100
ac
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