class Solution {
    public int minTaps(int n, int[] ranges) {

        List<Range> lranges= new ArrayList<>();

        for(int i =0;i<ranges.length;i++){
            int from = Math.max(0,i - ranges[i]);
            int to = Math.min(n, i + ranges[i]);
            int size = to - from;
            lranges.add(new Range(from,to,size));
        }

        Collections.sort(lranges);

        boolean[] watered = new boolean[n];

        int res = 0;

        for(Range r : lranges){
            boolean updated = false;
            for(int i = r.from;i<r.to;i++){
                if(watered[i] == false){
                    updated = true;
                }
                watered[i]=true;
            }
            if(updated){
                res++;
            }
            boolean fin = true;
            for(int i = 0;i<watered.length;i++){
                if(watered[i] == false){
                    fin = false;
                    break;
                }
            }

            if(fin == true){
                return res;
            }

        }

        return -1;
    }

        class Range implements Comparable<Range>{
        int from;
        int to;
        int size;

        public Range(int from, int to, int size) {
            this.from=from;
            this.to = to;
            this.size=size;
        }

        public int compareTo(Range other){
            return other.size - size;
        }
    }

}