E. Tracking Segments
题目大意：
给一个全为零的数组，m次询问区间，q次修改，定义一个区间中的1个数严格大于0个数为漂亮，问在第几次修改后出现了第一个完美区间。
思路：
对修改次数进行二分，利用前缀和判断区间中的1个数，时间复杂度为$mlog(q)$
code
int n, m;
int b[N];
vector<pii> a;
bool check(int op)
{
int pre[n + 1] = {0}, res[n + 1] = {0};
for (int i = 1; i <= op; ++i)
res[b[i]] = 1;
for (int i = 1; i <= n; ++i)
pre[i] = pre[i - 1] + res[i];
for (auto [l, r] : a)
if (2 * (pre[r] - pre[l - 1]) > r - l + 1)
return true;
return false;
}
void solved()
{
cin >> n >> m;
a.resize(m);
for (int i = 0; i < m; ++i)
{
int x, y;
cin >> x >> y;
a[i] = {x, y};
}
int q;
cin >> q;
for (int i = 1; i <= q; ++i)
{
int tot;
cin >> tot;
b[i] = tot;
}
int l = 0, r = q + 1;
while (l + 1 < r)
{
int mid = (l + r) >> 1;
if (check(mid))
r = mid;
else
l = mid;
}
if (r != q + 1)
cout << r << endl;
else
cout << -1 << endl;
}