adds 1856-maximum-subarray-min-product.java

Author: adhyyanT

Diff for: java/1856-maximum-subarray-min-product.java

@@ -0,0 +1,31 @@
+class Solution {
+    public int maxSumMinProduct(int[] nums) {
+        Stack<long[]> stack = new Stack<>(); // index, value
+        long[] pre = new long[nums.length];
+        pre[0] = nums[0];
+        long res = 0, mod = (int) 1e9 + 7;
+        for (int i = 1; i < nums.length; i++) {
+            pre[i] = pre[i - 1] + nums[i];
+        }
+        for (int i = 0; i < nums.length; i++) {
+            int idx = i;
+            while (stack.size() != 0 && nums[i] < stack.peek()[1]) {
+                long[] t = stack.pop();
+                int start = (int) t[0];
+                long value = t[1];
+                long sum = pre[i - 1] - ((start - 1) < 0 ? 0 : pre[start - 1]);
+                res = Math.max(res, (value * sum));
+                idx = start;
+            }
+            stack.push(new long[] { idx, nums[i] });
+        }
+        while (stack.size() != 0) {
+            long[] t = stack.pop();
+            int start = (int) t[0];
+            long value = t[1];
+            long sum = pre[nums.length - 1] - ((start - 1) < 0 ? 0 : pre[start - 1]);
+            res = Math.max(res, (value * sum));
+        }
+        return (int) ((res + mod) % mod);
+    }
+}