public class PlusOne { public int[] plusOne(int[] d) { int c = 0; d[d.length -1] += 1; for(int i = d.length -1; i >= 0; i--){ int sum = d[i] + c; d[i] = sum % 10; c = sum > 9 ? 1: 0; } if(c == 1){ int[] ans = new int[d.length+1]; ans[0] = 1; for(int i = 0; i < d.length; i++){ ans[i+1] = d[i]; } return ans; }else{ return d; } } }