Add leetcode 354

LeetCode-CN/354.cpp

@@ -0,0 +1,24 @@
+class Solution {
+public:
+    int maxEnvelopes(vector<vector<int>>& envelopes) {
+        const int N = envelopes.size();
+
+        sort(envelopes.begin(), envelopes.end(), [](vector<int>& a, vector<int>& b) {
+            return a[0] < b[0];
+            });
+
+        vector<int> dp(N);
+        for (int i = 0; i < N; i++) {
+            dp[i] = 1;
+        }
+        for (int i = 1; i < N; i++) {
+            for (int j = 0; j < i; j++) {
+                if (envelopes[i][0] > envelopes[j][0] && envelopes[i][1] > envelopes[j][1]) {
+                    dp[i] = max(dp[i], dp[j] + 1);
+                }
+            }
+        }
+
+        return *max_element(dp.begin(), dp.end());
+    }
+};