qsort
qosrt的这种写法,很简单,也很好理解。
一开始没看懂,因为这一句swap(v, left, (left + right)/2); 后来转念一想,不是把left当成分割点,而是把(left+right)/2当分割点,恍然大悟。
代码如下:
#include <stdio.h> void swap(int v[], int i, int j) { int t = v[i]; v[i] = v[j]; v[j] = t; } void qsort(int v[], int left, int right) { int i, last; if(left >= right) return ; swap(v, left, (left+right)/2); last = left; for (i = left+1; i<=right; i++) if (v[i] < v[left]) swap (v, ++last, i); swap(v, left, last); qsort(v, left, last-1); qsort(v, last+1, right); } int main(){ // int a[] = {-1, 32, 5, 1, 4}, i; int a[] = {32, -1, 5, 1, 4}, i; qsort(a, 0, 4); for (i=0; i<=4; i++) { printf("%d ", a[i]); } putchar('\n'); return 0; }