//打印从1到最大的n位数:大数问题,用字符串表示数字来避免溢出
bool increment(char* number){
bool isOverFlow = false;
int nTakeOver = 0;
size_t strLength = strlen(number);
for (size_t i = strLength - 1; i >= 0; --i){
int nSum = number[i] - '0' + nTakeOver;
if (i == strLength - 1)
nSum++;
if (nSum >= 10){
if (i == 0){
isOverFlow = true;
break;
}
nSum -= 10;
nTakeOver = 1;
number[i] = nSum + '0';
}
else{
number[i] = nSum + '0';
break;
}
}
return isOverFlow;
}
void printNumber(char* number){
size_t strLength = strlen(number);
int i = 0;
while (number[i] == '0') {i++;}
for (; i < strLength; ++i)
printf("%c", number[i]);
printf("\t");
}
void print1ToMaxOfNDigits(int n){
if (n <= 0)
return;
char* number = new char[n + 1];
memset(number, '0', n);
number[n] = '\0';
while (!increment(number))
printNumber(number);
delete []number;
return;
}
//方法二:全排列方法,递归实现
void print1ToMaxDigitsRecursively(char* number, int length, int index){
if (index == length - 1)
printNumber(number);
else{
for (int i = 0; i < 10; ++i){
number[index + 1] = '0' + i;
print1ToMaxDigitsRecursively(number, length, index+1);
}
}
}
void print1ToMaxOfNDigits2(int n){
if (n <= 0)
return;
char* number = new char[n + 1];
for (int i = 0; i < 10; ++i){
number[0] = i + '0';
print1ToMaxDigitsRecursively(number, n, 0);
}
return;
}