There is a cake factory producing K-flavored cakes. Flavors are numbered from 1 to K. A cake should consist of exactly K layers, each of a different flavor. It is very important that every flavor appears in exactly one cake layer and that the flavor layers are ordered from 1 to K from bottom to top. Otherwise the cake doesn't taste good enough to be sold. For example, for K = 3, cake [1, 2, 3] is well-prepared and can be sold, whereas cakes [1, 3, 2] and [1, 2, 3, 3] are not well-prepared.
The factory has N cake forms arranged in a row, numbered from 1 to N. Initially, all forms are empty. At the beginning of the day a machine for producing cakes executes a sequence of M instructions (numbered from 0 to M−1) one by one. The J-th instruction adds a layer of flavor C[J] to all forms from A[J] to B[J], inclusive.
What is the number of well-prepared cakes after executing the sequence of M instructions?
Write a function:
class Solution { public int solution(int N, int K, int[] A, int[] B, int[] C); }
that, given two integers N and K and three arrays of integers A, B, C describing the sequence, returns the number of well-prepared cakes after executing the sequence of instructions.
Examples:
1. Given N = 5, K = 3, A = [1, 1, 4, 1, 4], B = [5, 2, 5, 5, 4] and C = [1, 2, 2, 3, 3].
There is a sequence of five instructions:
The 0th instruction puts a layer of flavor 1 in all forms from 1 to 5.
The 1st instruction puts a layer of flavor 2 in all forms from 1 to 2.
The 2nd instruction puts a layer of flavor 2 in all forms from 4 to 5.
The 3rd instruction puts a layer of flavor 3 in all forms from 1 to 5.
The 4th instruction puts a layer of flavor 3 in the 4th form.
The picture describes the first example test.
The function should return 3. The cake in form 3 is missing flavor 2, and the cake in form 5 has additional flavor 3. The well-prepared cakes are forms 1, 2 and 5.
2. Given N = 6, K = 4, A = [1, 2, 1, 1], B = [3, 3, 6, 6] and C = [1, 2, 3, 4],
the function should return 2. The 2nd and 3rd cakes are well-prepared.
3. Given N = 3, K = 2, A = [1, 3, 3, 1, 1], B = [2, 3, 3, 1, 2] and C = [1, 2, 1, 2, 2],
the function should return 1. Only the 2nd cake is well-prepared.
4. Given N = 5, K = 2, A = [1, 1, 2], B = [5, 5, 3] and C = [1, 2, 1]
the function should return 3. The 1st, 4th and 5th cakes are well-prepared.
Write an efficient algorithm for the following assumptions:
N is an integer within the range [1..100,000];
M is an integer within the range [1..200,000];
each element of arrays A, B is an integer within the range [1..N];
each element of array C is an integer within the range [1..K];
for every integer J, A[J] ≤ B[J];
arrays A, B and C have the same length, equal to M.
// import java.util.*;
class Solution {
public int solution(int N, int K, int[] A, int[] B, int[] C) {
int[] first = new int[N]; // first
int[] last = new int[N]; // last
int[] num = new int[N]; // counts
for (int i = 0; i < A.length; i++) {
for (int current = A[i]-1; current <= B[i]-1; current++) {
num[current]++;
if (first[current] == 0) {
first[current] = C[i];
last[current] = C[i];
continue;
}
If (last[current] > C[I]) {
last[current] = Integer.MAX_VALUE;
} else {
last[current] = C[i];
}
}
}
int count = 0;
for (int i = 0; i < N; i++) {
if (((last[i] - first[i]) == (K - 1)) && (num[i] == K)) {
count++;
}
}
// StringBuilder sb = new StringBuilder();
// for (int i = 0; i < N; i++) {
// sb.append(last[i] + " ");
// }
// System.out.println(sb.toString());
return count;
}
}
Example test: (5, 3, [1, 1, 4, 1, 4], [5, 2, 5, 5, 4], [1, 2, 2, 3, 3])
OK
Example test: (6, 4, [1, 2, 1, 1], [3, 3, 6, 6], [1, 2, 3, 4])
OK
Example test: (3, 2, [1, 3, 3, 1, 1], [2, 3, 3, 1, 2], [1, 2, 1, 2, 2])
OK
Example test: (5, 2, [1, 1, 2], [5, 5, 3], [1, 2, 1])
OK
n_equal_to_1
✔
OK
▶
k_equal_to_1
✔
OK
▶
m_equal_to_1
✔
OK
▶
interval_contains_one_cake
✔
OK
▶
none_correct
✔
OK
