diff --git a/src/main/java/com/leetcode/1094.java b/src/main/java/com/leetcode/1094.java
new file mode 100644
index 0000000..63750d8
--- /dev/null
+++ b/src/main/java/com/leetcode/1094.java
@@ -0,0 +1,19 @@
+package com.leetcode;
+
+class Solution1094 {
+    public boolean carPooling(int[][] trips, int capacity) {
+        int[] passengers = new int[1001];
+        for (int[] trip: trips) {
+            passengers[trip[1]] += trip[0];
+            passengers[trip[2]] -= trip[0];
+        }
+        int cnt = 0;
+        for (int i: passengers) {
+            cnt += i;
+            if (cnt > capacity) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/1462.java b/src/main/java/com/leetcode/1462.java
new file mode 100644
index 0000000..5aef192
--- /dev/null
+++ b/src/main/java/com/leetcode/1462.java
@@ -0,0 +1,51 @@
+package com.leetcode;
+
+import javafx.beans.property.ReadOnlyIntegerWrapper;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+
+class Solution1462 {
+    public List<Boolean> checkIfPrerequisite(int numCourses, int[][] prerequisites, int[][] queries) {
+        HashSet<Integer>[] preDirectSet = new HashSet[numCourses];
+        HashSet<Integer>[] preSet = new HashSet[numCourses];
+        for (int[] prerequisite: prerequisites) {
+            if (preDirectSet[prerequisite[1]] == null) {
+                preDirectSet[prerequisite[1]] = new HashSet<>();
+            }
+            preDirectSet[prerequisite[1]].add(prerequisite[0]);
+        }
+
+        for (int i = 0; i < numCourses; i++) {
+            HashSet<Integer> tmp = new HashSet<>();
+            dfs(i, preDirectSet, tmp, new boolean[numCourses]);
+            preSet[i] = tmp;
+        }
+
+        List<Boolean> res = new ArrayList<>();
+        for (int[] query: queries) {
+            if (preSet[query[1]].contains(query[0])) {
+                res.add(true);
+            } else {
+                res.add(false);
+            }
+        }
+        return res;
+    }
+
+    private void dfs(int idx, HashSet<Integer>[] preDirectSet, HashSet<Integer> set, boolean[] visited) {
+        if (visited[idx]) {
+            return;
+        }
+        visited[idx] = true;
+        set.add(idx);
+        if (preDirectSet[idx] == null) {
+            return;
+        }
+        for (int next: preDirectSet[idx]) {
+            dfs(next, preDirectSet, set, visited);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/1465.java b/src/main/java/com/leetcode/1465.java
new file mode 100644
index 0000000..6f29551
--- /dev/null
+++ b/src/main/java/com/leetcode/1465.java
@@ -0,0 +1,23 @@
+package com.leetcode;
+
+import java.util.Arrays;
+
+class Solution1465 {
+    public int maxArea(int h, int w, int[] horizontalCuts, int[] verticalCuts) {
+        Arrays.sort(horizontalCuts);
+        int maxH = horizontalCuts[0];
+        for (int i = 1; i < horizontalCuts.length; i++) {
+            maxH = Math.max(maxH, horizontalCuts[i] - horizontalCuts[i-1]);
+        }
+        maxH = Math.max(maxH, h - horizontalCuts[horizontalCuts.length-1]);
+
+        Arrays.sort(verticalCuts);
+        int maxV = verticalCuts[0];
+        for (int i = 1; i < verticalCuts.length; i++) {
+            maxV = Math.max(maxV, verticalCuts[i] - verticalCuts[i-1]);
+        }
+        maxV = Math.max(maxV, w - verticalCuts[verticalCuts.length-1]);
+
+        return (int) (((long)maxV * (long)maxH) % (long)(1e9+7));
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/1670.java b/src/main/java/com/leetcode/1670.java
new file mode 100644
index 0000000..2d9a992
--- /dev/null
+++ b/src/main/java/com/leetcode/1670.java
@@ -0,0 +1,85 @@
+package com.leetcode;
+
+import jdk.nashorn.internal.ir.SplitReturn;
+
+import java.util.LinkedList;
+
+class FrontMiddleBackQueue {
+    // first-----head------last  first-------tail--------last
+    LinkedList<Integer> head;
+    LinkedList<Integer> tail;
+
+    public FrontMiddleBackQueue() {
+        this.head = new LinkedList<>();
+        this.tail = new LinkedList<>();
+    }
+
+    public void pushFront(int val) {
+        if (this.head.size() > this.tail.size()) {
+            this.tail.addFirst(this.head.removeLast());
+        }
+        this.head.addFirst(val);
+    }
+
+    public void pushMiddle(int val) {
+        if (this.head.size() > this.tail.size()) {
+            this.tail.addFirst(this.head.removeLast());
+        }
+        this.head.addLast(val);
+    }
+
+    public void pushBack(int val) {
+        this.tail.addLast(val);
+        if (this.head.size() < this.tail.size()) {
+            this.head.addLast(this.tail.removeFirst());
+        }
+    }
+
+    public int popFront() {
+        if (this.head.size() == 0) {
+            return -1;
+        }
+        int res = this.head.removeFirst();
+        if (this.head.size() < this.tail.size()) {
+            this.head.addLast(this.tail.removeFirst());
+        }
+        return res;
+    }
+
+    public int popMiddle() {
+        if (this.head.size() == 0) {
+            return -1;
+        }
+        int res = this.head.removeLast();
+        if (this.head.size() < this.tail.size()) {
+            this.head.addLast(this.tail.removeFirst());
+        }
+        return res;
+    }
+
+    public int popBack() {
+        if (this.tail.size() == 0) {
+            if (this.head.size() == 0) {
+                return -1;
+            } else {
+                return this.head.removeLast();
+            }
+        }
+        int res = this.tail.removeLast();
+        while(this.head.size() - this.tail.size() > 1) {
+            this.tail.addFirst(this.head.removeLast());
+        }
+        return res;
+    }
+}
+
+/**
+ * Your FrontMiddleBackQueue object will be instantiated and called as such:
+ * FrontMiddleBackQueue obj = new FrontMiddleBackQueue();
+ * obj.pushFront(val);
+ * obj.pushMiddle(val);
+ * obj.pushBack(val);
+ * int param_4 = obj.popFront();
+ * int param_5 = obj.popMiddle();
+ * int param_6 = obj.popBack();
+ */
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/1962.java b/src/main/java/com/leetcode/1962.java
new file mode 100644
index 0000000..8e5f9c7
--- /dev/null
+++ b/src/main/java/com/leetcode/1962.java
@@ -0,0 +1,22 @@
+package com.leetcode;
+
+import java.util.Comparator;
+import java.util.PriorityQueue;
+
+class Solution1962 {
+    public int minStoneSum(int[] piles, int k) {
+        int res = 0;
+        PriorityQueue<Integer> pq = new PriorityQueue<>((Comparator.comparingInt(o -> -o)));
+        for (int pile: piles) {
+            pq.add(pile);
+            res += pile;
+        }
+        for (int i = 0; i < k; i++) {
+            int v = pq.poll();
+            int minus = v/2;
+            res -= minus;
+            pq.add(v-minus);
+        }
+        return res;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/2661.java b/src/main/java/com/leetcode/2661.java
new file mode 100644
index 0000000..c369298
--- /dev/null
+++ b/src/main/java/com/leetcode/2661.java
@@ -0,0 +1,33 @@
+package com.leetcode;
+
+import javafx.util.Pair;
+
+class Solution2661 {
+    public int firstCompleteIndex(int[] arr, int[][] mat) {
+        int m = mat.length;
+        int n = mat[0].length;
+        int[] mCnt = new int[m];
+        int[] nCnt = new int[n];
+
+        int[][] idx = new int[m * n][2];
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                idx[mat[i][j]-1][0] = i;
+                idx[mat[i][j]-1][1] = j;
+            }
+        }
+
+        for (int i = 0; i < arr.length; i++) {
+            int[] p = idx[arr[i]];
+            mCnt[p[0]]++;
+            if (mCnt[p[0]] == n) {
+                return i;
+            }
+            nCnt[p[1]]++;
+            if (nCnt[p[1]] == m) {
+                return i;
+            }
+        }
+        return -1;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/leetcode/746.java b/src/main/java/com/leetcode/746.java
new file mode 100644
index 0000000..cbe8602
--- /dev/null
+++ b/src/main/java/com/leetcode/746.java
@@ -0,0 +1,15 @@
+package com.leetcode;
+
+class Solution746 {
+    public int minCostClimbingStairs(int[] cost) {
+        int[] dp = new int[cost.length + 1];
+        for (int i = 2; i < dp.length; i++) {
+            int v = dp[i-1] + cost[i-1];
+            if (i - 2 >= 0) {
+                v = Math.min(v, dp[i-2] + cost[i-2]);
+            }
+            dp[i] = v;
+        }
+        return dp[dp.length-1];
+    }
+}
\ No newline at end of file