add leetcode 718.cpp

Author: BWbwchen

leetcode/718.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    int findLength(vector<int>& nums1, vector<int>& nums2) {
+        // dp[i][j] = the lcs of nums1[0..i] and nums2[0..j]
+        // dp[i][j] = 0 if nums[i] != nums[j]
+        // dp[i][j] = dp[i-1][j-1]+1 if nums[i] == nums[j]
+        
+        int dp[1001][1001] = {0};
+        int ans = 0;
+        for (int i = 1; i <= nums1.size(); ++i) {
+            for (int j = 1; j <= nums2.size(); ++j) {
+                if (nums1[i-1] == nums2[j-1]) {
+                    dp[i][j] = dp[i-1][j-1] + 1;
+                    ans = max(ans, dp[i][j]);
+                }  
+            }
+        }
+        
+        return ans;
+    }
+};