update

leetcode/medium/712.cc

@@ -10,23 +10,22 @@ using std::string;
 using std::min;
 
 #define L 1000
-#define INF 1e8
 
 int dp[L + 1][L + 1];
 
 class Solution {
 public:
     int minimumDeleteSum(string s1, string s2) {
-        memset(dp, 0, sizeof(dp));
+        dp[0][0] = 0;
         for (int i = 1; i <= s1.size(); i++) { // The boundary is very important!
-            dp[i][0] = dp[i - 1][0] + s1.at(i - 1);
+            dp[i][0] = dp[i - 1][0] + s1[i - 1];
         }
         for (int j = 1; j <= s2.size(); j++) {
-            dp[0][j] = dp[0][j - 1] + s2.at(j - 1);
+            dp[0][j] = dp[0][j - 1] + s2[j - 1];
         }
         for (int i = 1; i <= s1.size(); i++) {
             for (int j = 1; j <= s2.size(); j++) {
-                int c1 = s1.at(i - 1), c2 = s2.at(j - 1);
+                int c1 = s1[i - 1], c2 = s2[j - 1];
                 int cost = min(dp[i - 1][j] + c1, dp[i][j - 1] + c2);
                 if (c1 == c2) {
                     dp[i][j] = min(dp[i - 1][j - 1], cost);