递归大总结之打印大数1-n

递归

#include<iostream> using namespace std; void PrintfNumber(char num[]) { bool isBegin0 = true; int nlength = strlen(num); for (int i = 0; i < nlength; ++i) { if (isBegin0&&num[i] != '0') { isBegin0 = false; } if (!isBegin0) { cout << num[i]; } } } void PrintToMaxDigits2(char *num, int length, int index) { if (index == length - 1) { PrintfNumber(num); return; } for (int i = 0; i < 10; i++) { num[index + 1] = i + '0'; PrintToMaxDigits2(num, length, index + 1);// } } void PrintToMaxofDigits(int n) { if (n <= 0) { return; } char *num = new char[n + 1]; num[n] = '\0'; for (int i = 0; i < 10; i++) { num[0] = i + '0'; PrintToMaxDigits2(num, n, 0); } } int main() { int n; cin >> n; PrintToMaxofDigits(n); system("pause"); }详解

//以n等于3为例 void PrintToMaxDigits2(char *num, int length, int index) { if (index == length - 1) { PrintfNumber(num); return; } for (int i = 0; i < 10; i++) { num[index + 1] = i + '0'; PrintToMaxDigits2(num, length, index + 1);// /* index=1； for (int i = 0; i < 10; i++) { num[index + 1] = i + '0'; PrintToMaxDigits2(num, 3, index + 1); if (index == length - 1) { //打印了1-9，这时num[1]还是1，当num[1]是2时再打印1-9 PrintfNumber(num); return; } } */ } }