URAL 1152 False Mirrors (DFS枚举)

/*本来想用贪心，每次挑能打中最多的怪的地方打，后来想想不行，因为如果有两个位置能打中一样多的怪，但是打中某个地方后会把剩下的怪弄得支离破碎，不好集中打*/
#include <stdio.h>
#define MAX_BALCONIES 20
#define INF 0xFFFFFFFF

int numOfBalconies;
int monstersArray[MAX_BALCONIES + 1];
int numOfMonsters;
int minDamage;

void shoot(int monstersLeft, int currentDamage){
	if (monstersLeft == 0){
		if (currentDamage < minDamage)
			minDamage = currentDamage;
		return;
	}

	int left, mid, right, monstersShooted, damage, temp1, temp2, temp3;
	for (mid = 1; mid <= numOfBalconies; mid++){
		if (monstersArray[mid] == 0)
			continue;
		left = mid == 1 ? numOfBalconies : mid - 1;
		right = mid == numOfBalconies ? 1 : mid + 1;
		monstersShooted = monstersArray[left] + monstersArray[mid] + monstersArray[right];
		damage = monstersLeft - monstersShooted;

		if (damage + currentDamage >= minDamage)
			continue;

		temp1 = monstersArray[left];
		temp2 = monstersArray[mid];
		temp3 = monstersArray[right];
		monstersArray[left] = monstersArray[mid] = monstersArray[right] = 0;
		shoot(monstersLeft - monstersShooted, currentDamage + damage);
		monstersArray[left] = temp1;
		monstersArray[mid] = temp2;
		monstersArray[right] = temp3;
	}
}

int main(){
	//freopen("input.txt", "r", stdin);
	scanf("%d\n", &numOfBalconies);
	int i;
	for (i = 1; i <= numOfBalconies; i++){
		scanf("%d", &monstersArray[i]);
		numOfMonsters += monstersArray[i];	
	}

	minDamage = INF;
	shoot(numOfMonsters, 0);
	printf("%d\n", minDamage);

	return 0;
}