Create Solution.js

Author: 07subhadip

solution/3400-3499/3430.Maximum and Minimum Sums of at Most Size K Subarrays/Solution.js

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+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var minMaxSubarraySum = function(nums, k) {
+    const computeSum = (nums, k, isMin) => {
+        const n = nums.length;
+        const prev = new Array(n).fill(-1);
+        const next = new Array(n).fill(n);
+        let stack = [];
+        
+        if (isMin) {
+            for (let i = 0; i < n; i++) {
+                while (stack.length > 0 && nums[stack[stack.length - 1]] >= nums[i]) {
+                    stack.pop();
+                }
+                prev[i] = stack.length > 0 ? stack[stack.length - 1] : -1;
+                stack.push(i);
+            }
+            stack = [];
+            for (let i = n - 1; i >= 0; i--) {
+                while (stack.length > 0 && nums[stack[stack.length - 1]] > nums[i]) {
+                    stack.pop();
+                }
+                next[i] = stack.length > 0 ? stack[stack.length - 1] : n;
+                stack.push(i);
+            }
+        } else {
+            for (let i = 0; i < n; i++) {
+                while (stack.length > 0 && nums[stack[stack.length - 1]] <= nums[i]) {
+                    stack.pop();
+                }
+                prev[i] = stack.length > 0 ? stack[stack.length - 1] : -1;
+                stack.push(i);
+            }
+            stack = [];
+            for (let i = n - 1; i >= 0; i--) {
+                while (stack.length > 0 && nums[stack[stack.length - 1]] < nums[i]) {
+                    stack.pop();
+                }
+                next[i] = stack.length > 0 ? stack[stack.length - 1] : n;
+                stack.push(i);
+            }
+        }
+
+        let sum = 0;
+        for (let i = 0; i < n; i++) {
+            const left = prev[i];
+            const right = next[i];
+            const a = left + 1;
+            const b = i;
+            const c = i;
+            const d = right - 1;
+
+            let s_start = Math.max(a, i - k + 1);
+            let s_end_candidate = d - k + 1;
+            let s_upper = Math.min(b, s_end_candidate);
+
+            let sum1 = 0;
+            if (s_upper >= s_start) {
+                const num_terms = s_upper - s_start + 1;
+                const first = s_start;
+                const last = s_upper;
+                const sum_s = (last * (last + 1)) / 2 - ((first - 1) * first) / 2;
+                const sum_k = (k - i) * num_terms;
+                sum1 = sum_s + sum_k;
+            }
+
+            let s2_start = s_upper + 1;
+            let s2_end = b;
+            s2_start = Math.max(s2_start, a);
+            s2_end = Math.min(s2_end, b);
+
+            let sum2 = 0;
+            if (s2_start <= s2_end) {
+                const count = s2_end - s2_start + 1;
+                const term = d - i + 1;
+                sum2 = term * count;
+            }
+
+            sum += nums[i] * (sum1 + sum2);
+        }
+        return sum;
+    };
+
+    const sumMin = computeSum(nums, k, true);
+    const sumMax = computeSum(nums, k, false);
+    return sumMin + sumMax;
+};