Create jump-game-iv.cpp

Author: kamyu104

C++/jump-game-iv.cpp

@@ -0,0 +1,33 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+public:
+    int minJumps(vector<int>& arr) {
+        unordered_map<int, vector<int>> groups;
+        for (int i = 0; i < arr.size(); ++i) {
+            groups[arr[i]].emplace_back(i);
+        }
+        int result = 0;
+        queue<pair<int, int>> q({{0, 0}});
+        unordered_set<int> lookup = {0};
+        while (!q.empty()) {
+            const auto [pos, step] = q.front(); q.pop();
+            if (pos == arr.size() - 1) {
+                result = step;
+                break;
+            }
+            unordered_set<int> neighbors(groups[arr[pos]].cbegin(),
+                                         groups[arr[pos]].cend());
+            groups[arr[pos]].clear();
+            neighbors.emplace(pos - 1), neighbors.emplace(pos + 1);
+            for (const auto& p : neighbors) {
+                if (0 <= p && p < arr.size() && !lookup.count(p)) {
+                    lookup.emplace(p);
+                    q.emplace(p, step + 1);
+                }
+            }
+        }
+        return result;
+    }
+};