Sunscreen （貪心+優先佇列）
阿新 • • 發佈：2019-01-08
To avoid unsightly burns while tanning, each of the C (1 ≤ C ≤ 2500) cows must cover her hide with sunscreen when they're at the beach. Cow i has a minimum and maximum SPF rating (1 ≤ minSPFi ≤ 1,000;
minSPFi ≤ maxSPFi ≤ 1,000) that will work. If the SPF rating is too low, the cow suffers sunburn; if the SPF rating is too high, the cow doesn't tan at all........
The cows have a picnic basket with L (1 ≤ L ≤ 2500) bottles of sunscreen lotion, each bottle i with an SPF rating SPFi (1 ≤ SPFi ≤ 1,000). Lotion bottle i can cover coveri cows with lotion. A cow may lotion from only one bottle.
What is the maximum number of cows that can protect themselves while tanning given the available lotions?
Input
* Line 1: Two space-separated integers: C and L
* Lines 2..C+1: Line i describes cow i's lotion requires with two integers: minSPFi and maxSPFi
* Lines C+2..C+L+1: Line i+C+1 describes a sunscreen lotion bottle i with space-separated integers: SPFi and coveri
Output
A single line with an integer that is the maximum number of cows that can be protected while tanning
Sample Input
3 2
3 10
2 5
1 5
6 2
4 1
Sample Output
2
題意：奶牛由兩個防晒程度值minspf和maxspf，由L種spf不一樣的防晒霜各有一定數量的瓶數。
要求防晒霜的spf的值大於奶牛的minspf且小於maxspf，問這些瓶數的防晒霜能最多能保護多少奶牛。
思路：貪心，優先佇列
要想得最優數量，首先得進行排序
防晒霜比較好處理，按照spf值從小到大排序
奶牛排序時按照最大值maxspf從小到大排序，如果最大值maxspf相同則按照最小值minspf從小到大排序。
因為maxspf大的值對spf的選擇的餘地更多，所以先優先處理maxspf小的，整體上升序處理奶牛與防晒霜spf。
The cows have a picnic basket with L (1 ≤ L ≤ 2500) bottles of sunscreen lotion, each bottle i with an SPF rating SPFi (1 ≤ SPFi ≤ 1,000). Lotion bottle i can cover coveri cows with lotion. A cow may lotion from only one bottle.
What is the maximum number of cows that can protect themselves while tanning given the available lotions?
Input
* Line 1: Two space-separated integers: C and L
* Lines 2..C+1: Line i describes cow i's lotion requires with two integers: minSPFi and maxSPFi
* Lines C+2..C+L+1: Line i+C+1 describes a sunscreen lotion bottle i with space-separated integers: SPFi and coveri
Output
A single line with an integer that is the maximum number of cows that can be protected while tanning
Sample Input
3 2
3 10
2 5
1 5
6 2
4 1
Sample Output
2
題意：奶牛由兩個防晒程度值minspf和maxspf，由L種spf不一樣的防晒霜各有一定數量的瓶數。
要求防晒霜的spf的值大於奶牛的minspf且小於maxspf，問這些瓶數的防晒霜能最多能保護多少奶牛。
思路：貪心，優先佇列
要想得最優數量，首先得進行排序
防晒霜比較好處理，按照spf值從小到大排序
奶牛排序時按照最大值maxspf從小到大排序，如果最大值maxspf相同則按照最小值minspf從小到大排序。
因為maxspf大的值對spf的選擇的餘地更多，所以先優先處理maxspf小的，整體上升序處理奶牛與防晒霜spf。
注意這裡每頭牛隻能使用一種防晒霜。
#include<cstdio> #include<cstring> #include<algorithm> using namespace std; struct node { int x; int y; }ci[2505],s[2505]; int cmp1(node a,node b) { return a.y==b.y?a.x<b.x:a.y<b.y; } int cmp2(node a,node b) { return a.x<b.x; } int main() { int c,l; int m,n; scanf("%d %d",&c,&l); for(int i=0;i<c;i++) scanf("%d %d",&ci[i].x,&ci[i].y); for(int i=0;i<l;i++) scanf("%d %d",&s[i].x,&s[i].y); sort(ci,ci+c,cmp1); sort(s,s+l,cmp2); int cnt=0; for(int i=0;i<c;i++) { for(int j=0;j<l;j++) { if(s[j].x>=ci[i].x&&s[j].x<=ci[i].y&&s[j].y>0) { cnt++; s[j].y--; break;//一頭牛隻能用一種 } } } printf("%d\n",cnt); return 0; }