凑钱
一.题目
二.思想
1.使用合并排序，稳定，也可以选择快排，但不稳定。也可以在一定数量下使用插入排序，在一定数量下使用其他高效率的排序方法。
2.使用二分查找最接近目标值的数。
三.代码 ps：审题没审清，题目给出的每种面额的money张数是不限的。下面代码是限制的，前面n个数是张数，后面n个是面额。但做法都是一样的。
#include<stdio.h>
#include<malloc.h>
typedef struct {
int count;
int money;
}arr;
int target;
int count = 0;
int n;
arr* list;
void merge(arr* temp, int left, int mid, int right) {
int l_pos = left;
int r_pos = mid + 1;
int pos = left;
while (l_pos <= mid && r_pos <= right) {
if (list[l_pos].money < list[r_pos].money)
temp[pos++] = list[l_pos++];
else
temp[pos++] = list[r_pos++];
}
while (l_pos <= mid)
temp[pos++] = list[l_pos++];
while (r_pos <= right)
temp[pos++] = list[r_pos++];
while (left <= right) {
list[left] = temp[left];
left++;
}
}
void sort(arr* temp, int left, int right) {
if (left < right) {
int mid = (left + right) / 2;
sort(temp, left, mid);
sort(temp, mid + 1, right);
merge(temp, left, mid, right);
}
}
void mergeSort() {
arr* temp = (arr*)malloc(sizeof(arr) * n);
if (temp != NULL) {
sort(temp, 0, n - 1);
free(temp);
}
}
void init() {
printf("请输入目标值target：");
scanf("%d", &target);
printf("请输入面值种类n：");
scanf("%d", &n);
printf("请输入张数与面值：");
list = (arr*)malloc(sizeof(arr) * n);
for (int i = 0; i < 2 * n; i++) {
if (i < n)
scanf("%d", &list[i].count);
else
scanf("%d", &list[i % n].money);
}
mergeSort();
}
int findNum(int left, int right, int target) {
if (left >= right)
return left;
int mid = (left + right) / 2;
if (list[mid].money == target)
return mid;
else if (list[mid].money < target)
findNum(mid + 1, right, target);
else
findNum(left, mid - 1, target);
}
void match() {
int right = n - 1;
while (right >= 0 && target > 0) {
right = findNum(0, right, target);
int need = target / list[right].money < list[right].count ? target / list[right].money : list[right].count;
target -= need * list[right].money;
count += need;
right--;
}
if (target > 0)
printf("Impossiable!");
else
printf("count=%d", count);
free(list);
}
int main() {
init();
match();
return 0;
}
