POJ 3614 Sun Bathing (贪心)

#include<stdio.h>
#include<malloc.h>
#define MAX 2501

int cows;
int bottles;
int minSPF[MAX];
int maxSPF[MAX];
int lotionSPF[MAX];
int covers[MAX];

struct node{
	int SPF;
	node *pNext;
};

node *head = NULL;//head of ordered list

/* consider 3 locations to insert */
void insert(int SPF){
	node *pNew = (node *)malloc(sizeof(node));
	pNew->SPF = SPF;
	pNew->pNext = NULL;
	if (head == NULL){
		head = pNew;
		return;
	}
	// insert to head
	if (SPF <= head->SPF){
		pNew->pNext = head;
		head = pNew;
		return;
	}
	node *pBefore = head;
	node *pAfter = head;
	while (pAfter != NULL  && pAfter->SPF <= SPF){
		pBefore = pAfter;
		pAfter= pAfter->pNext;
	}
	//insert to tail
	if (pAfter == NULL){
		pBefore->pNext = pNew;
		return;
	}
	//insert to middle
	pNew->pNext = pAfter;
	pBefore->pNext = pNew;
}

void quickSortBottles(int first, int last){
	if (first >= last){
		return;
	}
	while (first < last){
	int left = first;
	int right = last;
	int pivotValue = lotionSPF[left];
	int tempOfCover = covers[left];
	while (left < right){
		while (left < right && lotionSPF[right] >= pivotValue){
			right--;
		}
		lotionSPF[left] = lotionSPF[right];
		covers[left] = covers[right];
		while (left < right && lotionSPF[left] < pivotValue){
			left++;
		}
		lotionSPF[right] = lotionSPF[left];
		covers[right] = covers[left];		
	}
	lotionSPF[left] = pivotValue;
	covers[left] = tempOfCover;
	int pivot = left;
	quickSortBottles(first, pivot - 1);
	first = pivot + 1;
	}
}

void quickSortCows(int first, int last){
	if (first >= last){
		return;
	}
	while (first < last){
	int left = first;
	int right = last;
	int pivotValue = minSPF[left];
	int tempOfMaxSPF = maxSPF[left];
	while (left < right){
		while (left < right && minSPF[right] >= pivotValue){
			right--;
		}
		minSPF[left] = minSPF[right];
		maxSPF[left] = maxSPF[right];
		while (left < right && minSPF[left] < pivotValue){
			left++;
		}
		minSPF[right] = minSPF[left];
		maxSPF[right] = maxSPF[left];		
	}
	minSPF[left] = pivotValue;
	maxSPF[left] = tempOfMaxSPF;
	int pivot = left;
	quickSortCows(first, pivot - 1);
	first = pivot + 1;
	}
}

int main(){
	//freopen("input.txt", "r", stdin);
	/* input */
	scanf("%d %d", &cows, &bottles);
	int cow;
	for (cow = 1; cow <= cows; cow++){
		scanf("%d %d", &minSPF[cow], &maxSPF[cow]);
	}
	int bottle;
	for (bottle = 1; bottle <= bottles; bottle++){
		scanf("%d %d", &lotionSPF[bottle], &covers[bottle]);
	}
	/* sort */
	quickSortCows(1, cows);
	quickSortBottles(1, bottles);
	/* main loop: use bottles of lotions to cover cows */
	int cowsProtected = 0;
	cow = 1;
	for (bottle = 1; bottle <= bottles; bottle++){
		//insert cows whose minSPF less than lotionSPF into order list
		while (cow <= cows && minSPF[cow] <= lotionSPF[bottle]){
			insert(maxSPF[cow]);
			cow++;
		}
		//cover cows whose maxSPF bigger than lotionSPF in the list with lotions
		while (head != NULL && covers[bottle]){
			node *pTemp = head;
			head = head->pNext;
			if (pTemp->SPF >= lotionSPF[bottle]){
				covers[bottle]--;
				cowsProtected++;
			}
			free(pTemp);
		}
	}
	/* output */
	printf("%d", cowsProtected);
	return 0;
}