分治法找出数组中第二大数

#include <span style="font-family: Arial, Helvetica, sans-serif;"><iostream></span>using namespace std;class Res{public:int max;int secmax;};Res maxnum(int *a,int first,int last){int mid;Res res;if (last-first==1){if (a[first] > a[last]){res.max = a[first];res.secmax = a[last];}else{res.max = a[last];res.secmax = a[first];}return res;}if (last == first){return res;}else{mid = (first+last)>>1;if (maxnum(a, first, mid).max > maxnum(a, mid, last).max){res.max =maxnum(a, first, mid).max;res.secmax = maxnum(a, mid, last).max;}else{res.max = maxnum(a, mid, last).max;res.secmax = maxnum(a, first, mid).max;}return res;}}int main(int argc , const char * argv[]){int a[10] ={1,2,3,9,5,6,7,8,4,0};cout< return 0;}