day-15

Author: libterty

README.md

@@ -14,4 +14,5 @@
     -   Day 11: [Flood Fill](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-eleven/index.ts) :raising_hand:
     -   Day 12: [Single Element in a Sorted Array](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-twelve/index.ts) :hear_no_evil:
     -   Day 13: [Remove K Digits](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-thirteen/index.ts) :tongue:
-    -   Day 14: [Implement Trie (Prefix Tree)](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-thirteen/index.ts) :tongue:
+    -   Day 14: [Implement Trie (Prefix Tree)](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-thirteen/index.ts) :pig_nose:
+    -   Day 15: [Maximum Sum Circular Subarray](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-thirteen/index.ts) :whale:

src/may/day-fifteen/index.ts

@@ -0,0 +1,47 @@
+/**
+ * @param {number[]} A
+ * @return {number}
+ */
+
+let filterPostitives = (arr: number[]) => arr.every((i) => i > 0);
+let filterNegatives = (arr: number[]) => arr.every((i) => i < 0);
+
+var maxSubarraySumCircular = function (A: number[]): number {
+    if (A.length === 0 || filterNegatives(A)) return A.sort((a, b) => b - a)[0];
+    if (filterNegatives(A)) return A.reduce((a, b) => a + b, 0);
+
+    let i: number = 0;
+    let max_kadane: number = kadane(A);
+    let max_wrap: number = 0;
+
+    while (i < A.length) {
+        max_wrap += A[i];
+        A[i] = -A[i];
+        i++;
+    }
+
+    max_wrap = max_wrap + kadane(A);
+    return max_wrap > max_kadane ? max_wrap : max_kadane;
+};
+
+const kadane = (A: number[]): number => {
+    let i: number = 0;
+    let cur_max: number = 0;
+    let max_so_far: number = 0;
+
+    while (i < A.length) {
+        cur_max = Math.max(0, cur_max + A[i]);
+        max_so_far = Math.max(cur_max, max_so_far);
+        i++;
+    }
+
+    return max_so_far;
+};
+
+const sd = maxSubarraySumCircular([-3, -2, -1]);
+const sd1 = maxSubarraySumCircular([3, -1, 2, -1]);
+const sd2 = maxSubarraySumCircular([5, -3, 5]);
+
+console.log('a', sd);
+console.log('a', sd1);
+console.log('a', sd2);