剑指offer：从1到n整数中1出现的次数

题目：输入一个整数n，求从1到n这n个整数的十进制表示中1出现的次数。

private int iFactor = 1, iLower = 0, iCur = 0, iHigh = 0, iCount = 0;

	public int sum1(int N) {
		while (N / iFactor != 0) {
			iLower = N - (N / iFactor) * iFactor;
			iCur = (N / iFactor) % 10;
			iHigh = N / (10 * iFactor);
			switch (iCur) {
			case 0:
				iCount += iFactor * iHigh;
				break;
			case 1:
				iCount += iFactor * iHigh + iLower + 1;
				break;
			default:
				iCount += (iHigh + 1) * iFactor;
				break;
			}
			iFactor *= 10;
		}
		return iCount;
	}

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剑指offer：从1到n整数中1出现的次数

原文：http://blog.csdn.net/litianpenghaha/article/details/23937445