diff --git "a/leetcode3/\354\227\274\355\230\234\354\240\225/3701. Compute Alternating Sum.java" "b/leetcode3/\354\227\274\355\230\234\354\240\225/3701. Compute Alternating Sum.java"
new file mode 100644
index 00000000..54daa7e1
--- /dev/null
+++ "b/leetcode3/\354\227\274\355\230\234\354\240\225/3701. Compute Alternating Sum.java"	
@@ -0,0 +1,13 @@
+// 짝수는 더하고 홀수는 빼기
+// o(n)
+
+class Solution {
+    public int alternatingSum(int[] nums) {
+        int sum = 0;
+        for (int i = 0; i<nums.length; i++) {
+            if (i%2 == 0) sum += nums[i];
+            else sum -= nums[i];
+        }
+        return sum;
+    }
+}
diff --git "a/leetcode3/\354\227\274\355\230\234\354\240\225/785. Is Graph Bipartite?.java" "b/leetcode3/\354\227\274\355\230\234\354\240\225/785. Is Graph Bipartite?.java"
new file mode 100644
index 00000000..e4a73f48
--- /dev/null
+++ "b/leetcode3/\354\227\274\355\230\234\354\240\225/785. Is Graph Bipartite?.java"	
@@ -0,0 +1,27 @@
+// 인접한 노드는 다른 색
+
+class Solution {
+    public boolean isBipartite(int[][] graph) {
+        int[] color = new int[graph.length];
+
+        for (int i = 0; i<graph.length; i++) {
+            if (color[i] != 0) continue;
+
+            Queue<Integer> queue = new LinkedList<>();
+            queue.offer(i);
+            color[i] = 1;
+
+            while (!queue.isEmpty()) {
+                int node = queue.poll();
+                for (int next : graph[node]) {
+                    if (color[next] == color[node]) return false;
+                    else if (color[next] == 0) {
+                        color[next] = -color[node];
+                        queue.offer(next);
+                    }
+                }
+            }
+        }
+        return true;
+    }
+}