diff --git a/src/main/java/com/dota/binarySearch/_1642/Solution.java b/src/main/java/com/dota/binarySearch/_1642/Solution.java
new file mode 100644
index 0000000..b2a3dcc
--- /dev/null
+++ b/src/main/java/com/dota/binarySearch/_1642/Solution.java
@@ -0,0 +1,27 @@
+package com.dota.binarySearch._1642;
+
+import java.util.PriorityQueue;
+
+class Solution {
+	public int furthestBuilding(int[] heights, int bricks, int ladders) {
+		var p = new PriorityQueue<Integer>((a, b) -> b - a);
+		int n = heights.length;
+		for (int i = 1; i < n; i++) {
+			var diff = heights[i] - heights[i - 1];
+			if (diff <= 0) continue;
+
+			p.offer(diff);
+			if (bricks >= diff) {
+				bricks -= diff;
+			} else if (ladders > 0) {
+				ladders--;
+				bricks += p.poll();
+				bricks -= diff;
+				if (bricks < 0) return i - 1;
+			} else {
+				return i - 1;
+			}
+		}
+		return n - 1;
+	}
+}
\ No newline at end of file
diff --git a/src/main/java/com/dota/binarySearch/_1802/Solution.java b/src/main/java/com/dota/binarySearch/_1802/Solution.java
new file mode 100644
index 0000000..390183a
--- /dev/null
+++ b/src/main/java/com/dota/binarySearch/_1802/Solution.java
@@ -0,0 +1,32 @@
+package com.dota.binarySearch._1802;
+
+class Solution {
+	public int maxValue(int n, int index, int maxSum) {
+		int l = 1, r = maxSum + 1;
+		while (l + 1 < r) {
+			int mid = l + (r - l) / 2;
+			if (check(n, index, maxSum, mid)) {
+				l = mid;
+			} else {
+				r = mid;
+			}
+		}
+		return l;
+	}
+
+	boolean check(int n, int index, int maxSum, int k) {
+		long sum = 0;
+		int l = Math.max(0, index - k + 1);
+		sum += (long) (k + k - (index - l)) * (index - l + 1) / 2;
+		if (l > 0) {
+			sum += l;
+		}
+		int r = Math.min(index + k - 1, n - 1);
+		sum += (long) (k + k - (r - index)) * (r - index + 1) / 2;
+		if (r < n - 1) {
+			sum += n - r - 1;
+		}
+		sum -= k;
+		return sum <= maxSum;
+	}
+}
\ No newline at end of file