P1195 “非常男女”计划

#2, 类似前缀和的思想，以前OI的确用过这种思想，但昨天一时竟然没反应过来，太笨了。

需要注意的情况是如果0，1相同时要特殊处理，其下标就是长度（即若串是从1算起的话是0）。

评测结果
编译成功
测试数据 #0: Accepted, time = 15 ms, mem = 1252 KiB, score = 10
测试数据 #1: Accepted, time = 0 ms, mem = 1248 KiB, score = 10
测试数据 #2: Accepted, time = 0 ms, mem = 1256 KiB, score = 10
测试数据 #3: Accepted, time = 0 ms, mem = 1256 KiB, score = 10
测试数据 #4: Accepted, time = 0 ms, mem = 1252 KiB, score = 10
测试数据 #5: Accepted, time = 31 ms, mem = 1248 KiB, score = 10
测试数据 #6: Accepted, time = 93 ms, mem = 1252 KiB, score = 10
测试数据 #7: Accepted, time = 124 ms, mem = 1256 KiB, score = 10
测试数据 #8: Accepted, time = 140 ms, mem = 1252 KiB, score = 10
测试数据 #9: Accepted, time = 140 ms, mem = 1256 KiB, score = 10
Accepted, time = 543 ms, mem = 1256 KiB, score = 100

#include <iostream>
using namespace std;

int _tbl[2] = {-1, 1};

int _fs[200001], N;
#define fs(x)    _fs[(x) + 100000]

int main(void)
{
    int max = 0;
    int i, s;
    for(cin >> N, s = 0, i = 1; i<=N; ++i) {
        int o;
        cin >> o;
        s += _tbl[o];
        if (s) {
            if (!fs(s)) fs(s) = i;
            else if (max < i - fs(s)) max = i - fs(s);
        } else if (max < i) max = i;
    }
    cout << max << endl;
    return 0;
}