Add solution #436

Author: JoshCrozier

README.md

@@ -346,6 +346,7 @@
 433|[Minimum Genetic Mutation](./0433-minimum-genetic-mutation.js)|Medium|
 434|[Number of Segments in a String](./0434-number-of-segments-in-a-string.js)|Easy|
 435|[Non-overlapping Intervals](./0435-non-overlapping-intervals.js)|Medium|
+436|[Find Right Interval](./0436-find-right-interval.js)|Medium|
 437|[Path Sum III](./0437-path-sum-iii.js)|Medium|
 438|[Find All Anagrams in a String](./0438-find-all-anagrams-in-a-string.js)|Medium|
 441|[Arranging Coins](./0441-arranging-coins.js)|Easy|

solutions/0436-find-right-interval.js

@@ -0,0 +1,43 @@
+/**
+ * 436. Find Right Interval
+ * https://leetcode.com/problems/find-right-interval/
+ * Difficulty: Medium
+ *
+ * You are given an array of intervals, where intervals[i] = [starti, endi] and each
+ * starti is unique.
+ *
+ * The right interval for an interval i is an interval j such that startj >= endi and
+ * startj is minimized. Note that i may equal j.
+ *
+ * Return an array of right interval indices for each interval i. If no right interval
+ * exists for interval i, then put -1 at index i.
+ */
+
+/**
+ * @param {number[][]} intervals
+ * @return {number[]}
+ */
+var findRightInterval = function(intervals) {
+  const lookup = intervals.map(([start], i) => [start, i])
+    .sort((a, b) => a[0] - b[0]);
+  const result = new Array(intervals.length);
+
+  for (let i = 0; i < intervals.length; i++) {
+    const target = intervals[i][1];
+    let left = 0;
+    let right = lookup.length - 1;
+
+    while (left <= right) {
+      const middle = Math.floor((left + right) / 2);
+      if (lookup[middle][0] >= target) {
+        right = middle - 1;
+      } else {
+        left = middle + 1;
+      }
+    }
+
+    result[i] = left < lookup.length ? lookup[left][1] : -1;
+  }
+
+  return result;
+};