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.
implSolution{#[allow(dead_code)]pubfnmin_taps(n:i32,ranges:Vec<i32>)->i32{letmutlast=vec![0;(n+1)asusize];letmutans=0;letmutmx=0;letmutpre=0;// Initialize the last vectorfor(i,&r)inranges.iter().enumerate(){if(iasi32)-r>=0{last[((iasi32)-r)asusize]=std::cmp::max(last[((iasi32)-r)asusize],(iasi32)+r);}else{last[0]=std::cmp::max(last[0],(iasi32)+r);}}foriin0..nasusize{mx=std::cmp::max(mx,last[i]);ifmx<=(iasi32){return-1;}ifpre==(iasi32){ans+=1;pre=mx;}}ans}}