public int kEmptySlots(int[] flowers, int k) {

int n = flowers.length;

if (n <= 1) return -1;

int[] slot2days = new int[n+1];

for (int i=0; i<n; i++) {

slot2days[flowers[i]] = i+1;

}

int i = n-1;

int j = n;

int min = Integer.MAX_VALUE;

int ans = Integer.MAX_VALUE;

while (i > 0) {

if (slot2days[i] < slot2days[j]) {

if ((j - i - 1) == k) ans = Math.min(ans, Math.max(slot2days[i], slot2days[j]));

j--;

i = j-1;

min = Integer.MAX_VALUE;

} else if (slot2days[i] < min && slot2days[i] > slot2days[j]) {

if ((j - i - 1) == k) ans = Math.min(ans, Math.max(slot2days[i], slot2days[j]));

min = slot2days[i];

i--;

} else {

i--;

}

if ((j - i - 1) > k) {

j--;

i = j-1;

min = Integer.MAX_VALUE;

}

}

return ans < Integer.MAX_VALUE ? ans : -1;

}

/**

public int kEmptySlots2(int[] flowers, int k) {

int[] days = new int[flowers.length];

for (int i = 0; i < flowers.length; i++) {

days[flowers[i] - 1] = i + 1;

}

int ans = Integer.MAX_VALUE;

int left = 0, right = k+1;

search: while (right < days.length) {

for (int i = left+1; i < right; ++i) {

if (days[i] < days[left] || days[i] < days[right]) {

left = i;

right = i + k + 1;

continue search;

}

}

ans = Math.min(ans, Math.max(days[left], days[right]));

left = right;

right = left + k + 1;

}

return ans < Integer.MAX_VALUE ? ans : -1;

}