A. Flipping Game
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Iahub got bored, so he invented a game to be played on paper.
He writes n integers a1, a2, ..., an. Each of those integers can be either 0 or 1. He's allowed to do exactly one move: he chooses two indices i and j (1 ≤ i ≤ j ≤ n) and flips all values ak for which their positions are in range [i, j] (that is i ≤ k ≤ j). Flip the value of x means to apply operation x = 1 - x.
The goal of the game is that after exactly one move to obtain the maximum number of ones. Write a program to solve the little game of Iahub.
Input
The first line of the input contains an integer n (1 ≤ n ≤ 100). In the second line of the input there are n integers: a1, a2, ..., an. It is guaranteed that each of those n values is either 0 or 1.
Output
Print an integer — the maximal number of 1s that can be obtained after exactly one move.
Sample test(s)
Input
5
1 0 0 1 0
Output
4
Input
4
1 0 0 1
Output
4
Note
In the first case, flip the segment from 2 to 5 (i = 2, j = 5). That flip changes the sequence, it becomes: [1 1 1 0 1]. So, it contains four ones. There is no way to make the whole sequence equal to [1 1 1 1 1].
In the second case, flipping only the second and the third element (i = 2, j = 3) will turn all numbers into 1.
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 110
int main(){
int i,j,k,n,res,mx;
while(~scanf("%d",&n)){
for(i=1,k=mx=res=0;i<=n;i++){
scanf("%d",&j);
res+=j;
if(j==1){if(k>0)k--;}
else k++;
mx=max(mx,k);
}
res+=mx;
if(mx<=0)res--;
printf("%d\n",res);
}
return 0;
}
