g1401_1500.s1494_parallel_courses_ii.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g1401_1500.s1494_parallel_courses_ii
// #Hard #Dynamic_Programming #Bit_Manipulation #Graph #Bitmask
// #2023_06_13_Time_381_ms_(100.00%)_Space_37_MB_(100.00%)
class Solution {
fun minNumberOfSemesters(n: Int, relations: Array, k: Int): Int {
val pres = IntArray(n)
for (r in relations) {
val prev = r[0] - 1
val next = r[1] - 1
pres[next] = pres[next] or (1 shl prev)
}
val dp = IntArray(1 shl n)
dp.fill(n)
dp[0] = 0
for (mask in dp.indices) {
var canTake = 0
for (i in 0 until n) {
// already taken
if (mask and (1 shl i) != 0) {
continue
}
// satisfy all pres
if (mask and pres[i] == pres[i]) {
canTake = canTake or (1 shl i)
}
}
// loop each sub-masks
var take = canTake
while (take > 0) {
if (Integer.bitCount(take) > k) {
take = take - 1 and canTake
continue
}
dp[take or mask] = Math.min(dp[take or mask], dp[mask] + 1)
take = take - 1 and canTake
}
}
return dp[(1 shl n) - 1]
}
}