归并排序

今天上算法课程上面讲到的归并排序，回来写了个试试，弄了好多时间，真是费啊

void merge(int * p , int * q ,int * r, int length1,int length2){int i = 0;int j = 0;int k = 0;for(;i<length1&&j<length2;++k){if(p[i] < q[j]){r[k] = p[i];++i;}else if(p[i]> q[j]){r[k] = q[j];++j;}else{r[k] = p[i];i++;}}if(i < length1){for(;i<length1;++i){r[k++] = p[i];}}if(j< length2){for(;j<length2;++j){r[k++] = q[j];}}}void mergeSort(int * p,int * res, int length,int step){int times = length/step;for(int i =1 ;i <=times;++i){merge(p+(i-1)*step,p+i*step-step/2,res+(i-1)*step,step/2,step/2);for(int i = 0; i < 8;i++){cout<<res[i]<<", ";}cout<<endl;}}int log2(int x){if(x < 0)return -1;if(x<= 1&& x>0)return 0;double n = 1;double y = 2;while(1){if(x > pow(y,n)){++n;}else{break;}}return n;}int main(){int cnt = 8;int * p = new int[cnt];p[0] = 1;p[1] = 2;p[2] = 9;p[3] = 4;p[4] = 3;p[5] = 5;p[6] = 6;p[7] = 7;int * res = new int[8];memset(res,0,sizeof(int)*8);int times = log2(8);cout<<times<<endl;for(int i = 1; i<=times;++i){mergeSort(p,res,cnt,pow((double)2,(double)i));memcpy(p,res,cnt*sizeof(int));}system("pause");}