UVALive 6609 Minimal Subarray Length（RMQ-ST+二分）

#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
#define LC(x) (x<<1)
#define RC(x) ((x<<1)+1)
#define MID(x,y) ((x+y)>>1)
#define CLR(arr,val) memset(arr,val,sizeof(arr))
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);
typedef pair<int, int> pii;
typedef long long LL;
const double PI = acos(-1.0);
const int N = 500010;
LL arr[N];
LL Max[N][20];
LL prefix[N];

void init()
{
    CLR(Max, -0x3f3f3f3f3f3f3f3f);
    prefix[0] = 0LL;
}
void RMQ_init(int l, int r)
{
    int i, j;
    for (i = l; i <= r; ++i)
        Max[i][0] = max<LL>(Max[i][0], prefix[i]);
    for (j = 1; l + (1 << j) - 1 <= r; ++j)
    {
        for (i = l; i + (1 << j) - 1 <= r; ++i)
        {
            Max[i][j] = max<LL>(Max[i][j - 1], Max[i + (1 << (j - 1))][j - 1]);
        }
    }
}
LL ST(int l, int r)
{
    int k = log2(r - l + 1);
    return max<LL>(Max[l][k], Max[r - (1 << k) + 1][k]);
}
int main(void)
{
    int tcase, n, i;
    LL k;
    scanf("%d", &tcase);
    while (tcase--)
    {
        init();
        scanf("%d%lld", &n, &k);
        for (i = 1; i <= n; ++i)
        {
            scanf("%lld", &arr[i]);
            prefix[i] = prefix[i - 1] + arr[i];
        }
        RMQ_init(1, n);
        int ans = INF;
        for (i = 1; i <= n; ++i)
        {
            int L = i, R = n;
            int temp = -1;
            while (L <= R)
            {
                int mid = (L + R) >> 1;
                LL Get = ST(i, mid);
                if (Get - prefix[i - 1] >= k)
                {
                    temp = mid;
                    R = mid - 1;
                }
                else
                    L = mid + 1;
            }
            if (~temp)
                ans = min(ans, temp - i + 1);
        }
        printf("%d\n", ans == INF ? -1 : ans);
    }
    return 0;
}