#include using namespace std; int n, r; void dfs(int step, vector path, int m) { //过不了就减减枝吧,剩下的不够了,就别再继续了。 if (r - m > n - step) return; if (step == n + 1) return; if (m == r) { for (int i = 0; i < r; i++) printf("%3d", path[i]); printf("\n"); return; } //下一个数字选择上 vector p1 = path; p1.push_back(step + 1); dfs(step + 1, p1, m + 1); //下一个数字放弃掉 dfs(step + 1, path, m); } int main() { scanf("%d%d", &n, &r); dfs(0, {}, 0); return 0; }