Update maximum-running-time-of-n-computers.cpp

Author: kamyu104

C++/maximum-running-time-of-n-computers.cpp

@@ -15,3 +15,29 @@ class Solution {
         return total / n;
     }
 };
+
+// Time:  O(nlogr), r is the range of possible minutes
+// Space: O(1)
+// binary search
+class Solution2 {
+public:
+    long long maxRunTime(int n, vector<int>& batteries) {
+        auto check = [&n, &batteries](int64_t x) {
+            return accumulate(cbegin(batteries), cend(batteries), 0ll,
+                              [&x](const auto& total, const int64_t b) {
+                                  return total + min(b, x);
+                              }) >= n * x;
+        };
+        int64_t left = *min_element(cbegin(batteries), cend(batteries));
+        int64_t right = accumulate(cbegin(batteries), cend(batteries), 0ll) / n;
+        while (left <= right) {
+            const auto mid = left + (right - left) / 2;
+            if (!check(mid)) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return right;
+    }
+};