Minimum Number of Taps to Open to Water a Garden

There is a one-dimensional garden on the x-axis from 0 to n. There are n+1 taps located at x = 0, 1, ..., n. ranges[i] means the tap at position i can water [i - ranges[i], i + ranges[i]]. Return the minimum number of taps needed to water the entire garden [0, n], or -1 if impossible. Pattern: Greedy (same as Jump Game II / LC 45). Convert each tap to an interval, then greedily extend as far as possible at each step. Optimization: Build maxReach[l] = farthest right endpoint for intervals starting at l. Then scan left to right greedily. Example 1: Input: n = 5, ranges = [3,4,1,1,0,0] Output: 1 Explanation: Tap at 1 (range 4) covers [0,5] — entire garden. Example 2: Input: n = 3, ranges = [0,0,0,0] Output: -1