收集面试题（三）（计算一系列数字有多少指定数）

计算一系列数字有多少个指定字，例如1-12有5个1

public static void main(String[] args) {

		System.out.println(countNum(120000));
	}

	public static int countNum(int number) {

		int count = 0;

		StringBuffer buffer = new StringBuffer("");

		for (int i = 1; i <= number; i++) {
			buffer.append(i);
		}

		char[] chars = buffer.toString().toCharArray();

		for (char c : chars) {

			if (c == '1') {
				count++;
			}
		}

		return count;
	}