Create maximum-sum-obtained-of-any-permutation.cpp

Author: kamyu104

C++/maximum-sum-obtained-of-any-permutation.cpp

@@ -0,0 +1,51 @@
+// Time:  O(nlogn)
+// Space: O(n)
+
+class Solution {
+public:
+    int maxSumRangeQuery(vector<int>& nums, vector<vector<int>>& requests) {
+        static const int MOD = 1e9 + 7;
+
+        vector<int> count(size(nums));
+        for (const auto& req : requests) {
+            ++count[req[0]];
+            if (req[1] + 1 < size(count)) {
+                --count[req[1] + 1];
+            }
+        }
+        partial_sum(begin(count), end(count), begin(count));
+        sort(begin(nums), end(nums));
+        sort(begin(count), end(count));
+        int result = 0;
+        for (int i = 0; i < size(nums); ++i) {
+            result = addmod(result, mulmod(nums[i], count[i], MOD), MOD);
+        }
+        return result;
+    }
+
+private:
+    uint32_t addmod(uint32_t a, uint32_t b, uint32_t mod) {  // avoid overflow
+        a %= mod, b %= mod;
+        if (mod - a <= b) {
+            b -= mod;  // relied on unsigned integer overflow in order to give the expected results
+        }
+        return a + b;
+    }
+
+    // reference: https://stackoverflow.com/questions/12168348/ways-to-do-modulo-multiplication-with-primitive-types
+    uint32_t mulmod(uint32_t a, uint32_t b, uint32_t mod)  {  // avoid overflow
+        a %= mod, b %= mod;
+        uint32_t result = 0;
+        if (a < b) {
+            swap(a, b);
+        }
+        while (b > 0)  { 
+            if (b % 2 == 1) {
+                result = addmod(result, a, mod);
+            }
+            a = addmod(a, a, mod);
+            b /= 2; 
+        } 
+        return result; 
+    }
+};