Given a list of non negative integers, arrange them such that they form the largest number.
For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.
Note: The result may be very large, so you need to return a string instead of an integer.
[分析] 贪心思想,任两个数字字符串a, b, 若 a + b > b + a, 则a 应排在 b 前面。
注意点:
1.Arrays.sort()不支持给int数组传自定义比较器,因此需要转为String数组进行排序。
2.要判断并处理前缀为0的结果。
public class Solution {
Comparator<String> comparator = new Comparator<String>() {
public int compare(String a, String b) {
String result1 = a + b;
String result2 = b + a;
return result1.compareTo(result2);
}
};
public String largestNumber(int[] nums) {
if (nums == null || nums.length == 0)
return "";
int N = nums.length;
String[] numstrs = new String[N];
for (int i = 0; i < N; i++)
numstrs[i] = String.valueOf(nums[i]);
Arrays.sort(numstrs, comparator);
StringBuilder sb = new StringBuilder();
for (int i = N - 1; i >= 0; i--)
sb.append(numstrs[i]);
// truncate prefix 0
// style 1
/* if (sb.charAt(0) == '0' && N > 1) {
int j = 0;
while (j < sb.length() - 1 && sb.charAt(j) == '0')
j++;
sb.delete(0, j);
}
return sb.toString();*/
// style 2
int i = 0;
while (i < sb.length() && sb.charAt(i) == '0')
i++;
if (i == sb.length())
return "0";
else
return sb.substring(i, sb.length());
}
}