Thiruppathi · June 9, 2018 12:48 · Jun 9, 2018
diff --git a/missingInteger.js b/missingInteger.js
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+/*  Missing Integer - Codility
+This is a demo task.
+
+Write a function:
+
+function solution(A);
+
+that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.
+
+For example, given A = [1, 3, 6, 4, 1, 2], the function should return 5.
+
+Given A = [1, 2, 3], the function should return 4.
+
+Given A = [−1, −3], the function should return 1.
+
+Assume that:
+
+N is an integer within the range [1..100,000];
+each element of array A is an integer within the range [−1,000,000..1,000,000].
+Complexity:
+
+expected worst-case time complexity is O(N);
+expected worst-case space complexity is O(N) (not counting the storage required for input arguments).
+
+*/
+
+function solution(A) {
+  A.sort(comparator);
+  return A.reduce((prev, next) => {
+    if (next > -1 && next === prev) {
+      prev++;
+    }
+    return prev;
+  }, 1);
+}
+
+// Sort the array explicit way
+function comparator(a, b) {
+  return a - b;
+}
+
+console.log(solution([1, 3, 6, 4, 1, 2])); // 5
+console.log(solution([1, 2, 3])); // 4
+console.log(solution([-1, -3])); // 1
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