# POJ3185 The Water Bowls 反转（开关）

Description

The cows have a line of 20 water bowls from which they drink. The bowls can be either right-side-up (properly oriented to serve refreshing cool water) or upside-down (a position which holds no water). They want all 20 water bowls to be right-side-up and thus
use their wide snouts to flip bowls.

Their snouts, though, are so wide that they flip not only one bowl but also the bowls on either side of that bowl (a total of three or -- in the case of either end bowl -- two bowls).

Given the initial state of the bowls (1=undrinkable, 0=drinkable -- it even looks like a bowl), what is the minimum number of bowl flips necessary to turn all the bowls right-side-up?

Input

Line 1: A single line with 20 space-separated integers

Output

Line 1: The minimum number of bowl flips necessary to flip all the bowls right-side-up (i.e., to 0). For the inputs given, it will always be possible to find some combination of flips that will manipulate the bowls to 20 0‘s.

Sample Input

0 0 1 1 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0

Sample Output

3

Hint

Explanation of the sample:

Flip bowls 4, 9, and 11 to make them all drinkable:

0 0 1 1 1 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 [initial state]

0 0 0 0 0 0 0 1 1 0 1 1 0 0 0 0 0 0 0 0 [after flipping bowl 4]

0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 [after flipping bowl 9]

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 [after flipping bowl 11]

1，反转的先后顺序是不重要的；

2，主动对一个开关进行2次或2次以上的反转是多余的。

#include <stdio.h>
#include <vector>
#include <math.h>
#include <string.h>
#include <string>
#include <iostream>
#include <queue>
#include <list>
#include <algorithm>
#include <stack>
#include <map>

using namespace std;

int main()
{
#ifdef _DEBUG
freopen("e:\\in.txt", "r", stdin);
#endif
int side[21];
int side1[21];
for (int i = 0; i < 20; i ++)
{
scanf("%d", &side[i]);
}
int minCount = 50;
for (int i = 0; i < 4;i++)
{
int count1 = 0;
memcpy(side1, side, sizeof(side));
if (i == 1)
{
side1[0]++;
side1[1]++;
count1++;
}
else if (i == 2)
{
side1[18]++;
side1[19]++;
count1++;
}
else if (i == 3)
{
side1[0]++;
side1[1]++;
side1[18]++;
side1[19]++;
count1++;
count1++;
}
for (int i = 0; i <= 17; i++)
{
if (side1[i] & 1)
{
side1[i] ++;
side1[i + 1]++;
side1[i + 2]++;
count1++;
}
}
if (!(side1[1] & 1 || side1[18] & 1 || side1[19] & 1))
{
if (minCount > count1)
{
minCount = count1;
}
}
}
printf("%d\n", minCount);
return 1;
}

## poj 3185 The Water Bowls（高斯消元）

The Water Bowls Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4352   Accepted: 1721 Description The cows have a line of 20 water bowls from which they drink. The bowls can be either right-side-up (properly oriented to serve refreshing

## poj3185--The Water Bowls(高斯消元问题3)

The Water Bowls Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4623   Accepted: 1812 Description The cows have a line of 20 water bowls from which they drink. The bowls can be either right-side-up (properly oriented to serve refreshing