{ "data": { "question": { "questionId": "1451", "questionFrontendId": "1326", "boundTopicId": null, "title": "Minimum Number of Taps to Open to Water a Garden", "titleSlug": "minimum-number-of-taps-to-open-to-water-a-garden", "content": "

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).

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There are n + 1 taps located at points [0, 1, ..., n] in the garden.

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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.

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Return the minimum number of taps that should be open to water the whole garden, If the garden cannot be watered return -1.

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Example 1:

\n\"\"\n
\nInput: n = 5, ranges = [3,4,1,1,0,0]\nOutput: 1\nExplanation: The tap at point 0 can cover the interval [-3,3]\nThe tap at point 1 can cover the interval [-3,5]\nThe tap at point 2 can cover the interval [1,3]\nThe tap at point 3 can cover the interval [2,4]\nThe tap at point 4 can cover the interval [4,4]\nThe tap at point 5 can cover the interval [5,5]\nOpening Only the second tap will water the whole garden [0,5]\n
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Example 2:

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\nInput: n = 3, ranges = [0,0,0,0]\nOutput: -1\nExplanation: Even if you activate all the four taps you cannot water the whole garden.\n
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Constraints:

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