l1776 区间 dp问题 注意初始化条件即可

Leetcode/L1776.cpp

@@ -0,0 +1,61 @@
+#include <algorithm>
+#include <cmath>
+#include <functional>
+#include <iostream>
+#include <map>
+#include <queue>
+#include <set>
+#include <stack>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+using namespace std;
+const int MAX_VALUE = 0x7FFFFFFF, MIN_VALUE = 0x80000000, INF = 0x3F3F3F3F, kMod = 1E9 + 7;
+#define fastio                                                                                                                                                                                         \
+  ios_base::sync_with_stdio(false);                                                                                                                                                                    \
+  cin.tie(0);                                                                                                                                                                                          \
+  cout.tie(0);
+#define debug puts("pigtoria bling bling ⚡️⚡️");
+#define FOR(i, a, b) for (int i = a; i < b; i++)
+#define pii pair<int, int>
+#define LL long long
+#define LD long double
+#define PB push_back
+#define EB emplace_back
+#define MP make_pair
+#define FI first
+#define SE second
+
+// tag: 区间 dp
+// xx[x]0000[x]xx
+//    i      j
+// dp[i][j]=dp[i-1][j]+nums[i]*mult[i+j] ,  dp[i][j-1]+nums[n-j+1]*mult[i+j]， i
+class Solution {
+public:
+  int maximumScore(vector<int> &nums, vector<int> &multipliers) {
+    int n = nums.size();
+    int m = multipliers.size();
+    auto dp = vector<vector<int>>(m + 1, vector<int>(m + 1, -INF));
+    nums.insert(nums.begin(), 0);
+    dp[0][0] = 0;
+
+    int ans = -INF;
+    for (int len = 1; len <= m; ++len) {
+      for (int i = 0; i <= len; ++i) {
+        int j = len - i;
+        if (i >= 1) {
+          dp[i][j] = max(dp[i][j], dp[i - 1][j] + nums[i] * multipliers[len - 1]);
+        }
+        if (j >= 1) {
+          dp[i][j] = max(dp[i][j], dp[i][j - 1] + nums[n - j + 1] * multipliers[len - 1]);
+        }
+        if (len == m) {
+          ans = max(ans, dp[i][j]);
+        }
+      }
+    }
+    return ans;
+  }
+
+};