1 public class Solution { 2     public List<String> findMissingRanges(int[] A, int lower, int upper) { 3         //for a range lower-upper, and a number A[i], we have conditions: 4         //1. A[i]<lower: move to i+1; 5         //2. A[i]==lower: lower -> A[i]+1 6         //3. lower<A[i]<=upper: generate a range: lower->A[i]-1; lower becomes A[i]+1. NOTE A[i]==upper: end of the program. 7         //4. A[i]>upper: get range: lower->upper, end of the problem. 8  9         List<String> res = new ArrayList<String>();10 11         for (int i=0;i<A.length;i++){12             if (A[i]<lower) continue;13            14             if (A[i]==lower){15                 lower=A[i]+1;16                 continue;17             }18 19             if (A[i]>lower && A[i]<=upper){20                 String range = "";21                 if (lower!=A[i]-1) range = Integer.toString(lower)+"->"+Integer.toString(A[i]-1);22                 else range = Integer.toString(lower);23                 res.add(range);24                 lower = A[i]+1;25                 if (A[i]==upper) break;26                 else continue;27             }28 29             if (A[i]>upper){30                 String range = "";31                 if (lower!=upper) range = Integer.toString(lower)+"->"+Integer.toString(upper);32                 else range = Integer.toString(lower);33                 res.add(range);34                 lower = A[i]+1;35                 break;36             }37         }38 39         if (lower<=upper){40             String range = "";41             if (lower!=upper) range = Integer.toString(lower)+"->"+Integer.toString(upper);42             else range = Integer.toString(lower);43             res.add(range);44         }45 46         return res;47     }48 }