cpp: add “1235. Maximum Profit in Job Scheduling”

Signed-off-by: Matej Focko <mfocko@redhat.com>

cpp/maximum-profit-in-job-scheduling.cpp

@@ -0,0 +1,79 @@
+#include <algorithm>
+#include <cassert>
+#include <vector>
+
+class Solution {
+    struct job_t {
+        int start;
+        int end;
+        int profit;
+
+        auto operator<=>(const job_t &other) const {
+            if (start != other.start) {
+                return start <=> other.start;
+            }
+
+            if (end != other.end) {
+                return end <=> other.end;
+            }
+
+            return profit <=> other.profit;
+        }
+    };
+
+    int find(const std::vector<job_t> &jobs, std::vector<int> &dp,
+             std::size_t i) {
+        // out of bounds
+        if (i >= jobs.size()) {
+            return 0;
+        }
+
+        // already precomputed
+        if (dp[i] != -1) {
+            return dp[i];
+        }
+
+        auto next_index =
+            std::lower_bound(jobs.begin(), jobs.end(), jobs[i],
+                             [](const job_t &next, const job_t &current) {
+                                 return next.start < current.end;
+                             }) -
+            jobs.begin();
+
+        int if_picked = jobs[i].profit + find(jobs, dp, next_index);
+        int if_skipped = find(jobs, dp, i + 1);
+        dp[i] = std::max(if_picked, if_skipped);
+
+        return dp[i];
+    }
+
+  public:
+    int jobScheduling(const std::vector<int> &startTime,
+                      const std::vector<int> &endTime,
+                      const std::vector<int> &profit) {
+        std::vector<job_t> jobs;
+        for (auto i = 0u; i < profit.size(); ++i) {
+            jobs.push_back({startTime[i], endTime[i], profit[i]});
+        }
+        std::sort(jobs.begin(), jobs.end());
+
+        std::vector<int> dp(profit.size(), -1);
+        find(jobs, dp, 0);
+
+        return dp[0];
+    }
+};
+
+int main() {
+    Solution s;
+
+    assert(s.jobScheduling(std::vector{1, 2, 3, 3}, std::vector{3, 4, 5, 6},
+                           std::vector{50, 10, 40, 70}) == 120);
+    assert(s.jobScheduling(std::vector{1, 2, 3, 4, 6},
+                           std::vector{3, 5, 10, 6, 9},
+                           std::vector{20, 20, 100, 70, 60}) == 150);
+    assert(s.jobScheduling(std::vector{1, 1, 1}, std::vector{2, 3, 4},
+                           std::vector{5, 6, 4}) == 6);
+
+    return 0;
+}