codeforces--873b--balanced Substring

B. Balanced Substring time limit/test 1 second memory limit per test 256 megabytes input standard input output Standar D Output

You are are given a string s consisting only of characters 0 and 1. A substring [L, R] of S is a string SLSL + 1SL + 2 ... SR, and its length equals to R-l + 1. A substring is called balanced if the number of zeroes (0) equals to the number of ones in this substring.

You are have to determine the length of the longest balanced substring of s. Input

The contains n (1≤n≤100000)-the number of characters in S.

The second line contains a string s consisting of exactly n characters. Only characters 0 and 1 can appear in S. Output

If There is no non-empty balanced substring in s, print 0. Otherwise, print the length of the longest balanced substring. Examples input

8
11010111

Output

4

Input

3
111

Output

0

Note

In the "the" example you can choose the substring [3, 6]. It is balanced, and its length is 4. Choosing the substring [2, 5] is also possible.

In the second example it's impossible to find a non-empty balanced substring.

String processing,.. Ask the length of the longest paragraph string (equal to the number of 1 and 0).

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
using namespace std;
const int LEN=1E5;
int main ()
{
    int n,com[100008];
    Char s[100008];
    while (~SCANF ("%d%s", &n,s)) {
        int sum;
        com[0]=2* (s[0]-48)-1;
        for (int i=1;i<n;i++)
            com[i]=com[i-1]+2* (s[i]-48)-1;
        int str[200008];
        memset (str,-1,sizeof str);
        for (int i=0;i<n;i++)
            if (str[len+com[i]]==-1) str[len+com[i]]=i;
        Str[len]=-1;
        int ans=0;
        for (int i=0;i<n;i++)
            Ans=max (Ans,i-str[len+com[i]);
        printf ("%d\n", ans);
    }
    return 0;
}