袋子有五种颜色球若干，每次取三种不一样颜色的球，有多少种取法
/*排列组合做法*/ #include<stdio.h> int main() { int n = 1, m = 1, sum = 1, w = 1, q = 1; printf("请输入排列总数n和抽取的数m:"); scanf_s("%d%d", &n, &m);//C用scanf() for (int i = 1; i < n;) w *= ++i; for (int j = 1; j < m;) q *= ++j; for (int i = 1; i < n - m;) sum *= ++i; sum = w / (q*sum); printf("%d", sum); getchar(); getchar(); return 0; } /*就题论题直接做*/ #include <stdio.h> int main() { int i,j,k,sum=0; for (i = 0; i < 4; i++)//把五种颜色球抽象为数字1 2 3 4 5 for (j = 4; j> i; j--) for (k = j- 1; k > i; k--) sum = sum + 1;//计算可循环的次数就是取球的方法种类 printf("%d", sum); getchar(); return 0; }