Add solution #1575

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,378 LeetCode solutions in JavaScript
+# 1,379 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1202,6 +1202,7 @@
 1572|[Matrix Diagonal Sum](./solutions/1572-matrix-diagonal-sum.js)|Easy|
 1573|[Number of Ways to Split a String](./solutions/1573-number-of-ways-to-split-a-string.js)|Medium|
 1574|[Shortest Subarray to be Removed to Make Array Sorted](./solutions/1574-shortest-subarray-to-be-removed-to-make-array-sorted.js)|Medium|
+1575|[Count All Possible Routes](./solutions/1575-count-all-possible-routes.js)|Hard|
 1576|[Replace All ?'s to Avoid Consecutive Repeating Characters](./solutions/1576-replace-all-s-to-avoid-consecutive-repeating-characters.js)|Medium|
 1598|[Crawler Log Folder](./solutions/1598-crawler-log-folder.js)|Easy|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|

solutions/1575-count-all-possible-routes.js

@@ -0,0 +1,51 @@
+/**
+ * 1575. Count All Possible Routes
+ * https://leetcode.com/problems/count-all-possible-routes/
+ * Difficulty: Hard
+ *
+ * You are given an array of distinct positive integers locations where locations[i] represents
+ * the position of city i. You are also given integers start, finish and fuel representing the
+ * starting city, ending city, and the initial amount of fuel you have, respectively.
+ *
+ * At each step, if you are at city i, you can pick any city j such that j != i and
+ * 0 <= j < locations.length and move to city j. Moving from city i to city j reduces the
+ * amount of fuel you have by |locations[i] - locations[j]|. Please notice that |x| denotes
+ * the absolute value of x.
+ *
+ * Notice that fuel cannot become negative at any point in time, and that you are allowed to visit
+ * any city more than once (including start and finish).
+ *
+ * Return the count of all possible routes from start to finish. Since the answer may be too large,
+ * return it modulo 109 + 7.
+ */
+
+/**
+ * @param {number[]} locations
+ * @param {number} start
+ * @param {number} finish
+ * @param {number} fuel
+ * @return {number}
+ */
+var countRoutes = function(locations, start, finish, fuel) {
+  const MOD = 1e9 + 7;
+  const memo = new Array(locations.length).fill().map(() => new Array(fuel + 1).fill(-1));
+
+  function calculateRoutes(currentCity, remainingFuel) {
+    if (remainingFuel < 0) return 0;
+    if (memo[currentCity][remainingFuel] !== -1) return memo[currentCity][remainingFuel];
+
+    let routes = currentCity === finish ? 1 : 0;
+
+    for (let nextCity = 0; nextCity < locations.length; nextCity++) {
+      if (nextCity !== currentCity) {
+        const fuelCost = Math.abs(locations[currentCity] - locations[nextCity]);
+        routes = (routes + calculateRoutes(nextCity, remainingFuel - fuelCost)) % MOD;
+      }
+    }
+
+    memo[currentCity][remainingFuel] = routes;
+    return routes;
+  }
+
+  return calculateRoutes(start, fuel);
+};