https://leetcode.cn/problems/number-of-beautiful-partitions

Author: masx200

README.md

@@ -45,6 +45,8 @@ Step 2. Add the dependency
 
 <summary>展开查看</summary>
 
+https://leetcode.cn/problems/number-of-beautiful-partitions
+
 https://leetcode.cn/problems/minimum-fuel-cost-to-report-to-the-capital
 
 https://leetcode.cn/problems/closest-nodes-queries-in-a-binary-search-tree

number-of-beautiful-partitions/index.ts

@@ -0,0 +1,33 @@
+function beautifulPartitions(s: string, k: number, minLength: number): number {
+    const MOD = 1e9 + 7;
+    const l = minLength;
+
+    const n = s.length;
+    if (k * l > n || !isPrime(s[0]) || isPrime(s[n - 1])) {
+        // 剪枝
+        return 0;
+    }
+    const f = Array(k + 1)
+        .fill(0)
+        .map(() => Array<number>(n + 1).fill(0));
+    f[0][0] = 1;
+    for (let i = 1; i <= k; ++i) {
+        let sum = 0;
+        // 优化：枚举的起点和终点需要给前后的子串预留出足够的长度
+        for (let j = i * l; j + (k - i) * l <= n; j++) {
+            if (canPartition(s, j - l)) sum = (sum + f[i - 1][j - l]) % MOD; // j'=j-l 双指针
+            if (canPartition(s, j)) f[i][j] = sum;
+        }
+    }
+    return f[k][n];
+}
+
+function isPrime(c: string) {
+    return c == "2" || c == "3" || c == "5" || c == "7";
+}
+
+// 判断是否可以在 j-1 和 j 之间分割（开头和末尾也算）
+function canPartition(s: string, j: number) {
+    return j == 0 || j == s.length || (!isPrime(s[j - 1]) && isPrime(s[j]));
+}
+export default beautifulPartitions;