算法—背包问题
参考:趣学算法
代码:
typedef struct three {float w;float v;float p;
}three;
#define elemType three
int quickSort1(elemType a[], int l, int h) {//快速排序int i = l, j = h;elemType p1 = a[i];while (i < j) {while (i<j&&a[j].p>=p1.p) {//从右往左遍历查找比p1更小的元素j--;}if (i < j) {a[i++] = a[j];}while (i < j&&a[i].p < p1.p) {//从左往右遍历查找比p1更大的元素i++;}if (i < j) {a[j--] = a[i];}}a[i] = p1;//分界的值,左边小于等于p1,右边大于p1return i;
}
void fenZhi1(elemType a[], int l, int h) {//分治if (l < h) {int mid = quickSort1(a, l, h);//以mid为分界线,进行分治,然后递归下去排序fenZhi1(a, l, mid - 1);fenZhi1(a, mid + 1, h);}
}
#include <stdio.h>
#include <stdlib.h>
#include"quickSort1.h"
int main() {elemType a[100];int num,i=0;scanf_s("%d", &num);while (i<num) {scanf_s("%f%f", &a[i].w,&a[i].v);a[i].p = a[i].v / a[i].w;i++;}fenZhi1(a, 0, num-1);//调动分治策略实现所有趟快速排序,而不是调用快速排序一趟进排序for (i = 0; i < num; i++) {printf("%f %f %f\n", a[i].w, a[i].v, a[i].p);}float sum = 0.0,maxValue=0.0,acceptWeight;scanf_s("%f", &acceptWeight);for (i = num-1; i>=0; i--) {if (sum + a[i].w <= acceptWeight) {sum += a[i].w;maxValue += a[i].v;}else {maxValue += (acceptWeight - sum)*a[i].p;sum += (acceptWeight - sum);//装满 break;}}printf("背包问题获得的最大值:%f\n", maxValue);system("pause");return 0;
}
测试截图:
时间复杂度O(nlogn),空间复杂度O(n)
彩蛋:不可分的0-1问题如何寻找最优值??
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