POTD 2026-07-08 solved

src/3700-3799/3756.cpp

@@ -0,0 +1,145 @@
+/*
+Tags
+level-medium
+math, string, prefix-sum
+
+Problem Description
+3756. Concatenate Non-Zero Digits and Multiply by Sum II
+
+You are given a string s of length m consisting of digits. You are also given a 2D integer array queries, where queries[i] = [li, ri].
+For each queries[i], extract the substring s[li..ri]. Then, perform the following:
+Form a new integer x by concatenating all the non-zero digits from the substring in their original order. If there are no non-zero digits, x = 0.
+Let sum be the sum of digits in x. The answer is x * sum.
+Return an array of integers answer where answer[i] is the answer to the ith query.
+Since the answers may be very large, return them modulo 109 + 7.
+
+Example 1:
+Input: s = "10203004", queries = [[0,7],[1,3],[4,6]]
+Output: [12340, 4, 9]
+Explanation:
+s[0..7] = "10203004"
+x = 1234
+sum = 1 + 2 + 3 + 4 = 10
+Therefore, answer is 1234 * 10 = 12340.
+s[1..3] = "020"
+x = 2
+sum = 2
+Therefore, the answer is 2 * 2 = 4.
+s[4..6] = "300"
+x = 3
+sum = 3
+Therefore, the answer is 3 * 3 = 9.
+
+Example 2:
+Input: s = "1000", queries = [[0,3],[1,1]]
+Output: [1, 0]
+Explanation:
+s[0..3] = "1000"
+x = 1
+sum = 1
+Therefore, the answer is 1 * 1 = 1.
+s[1..1] = "0"
+x = 0
+sum = 0
+Therefore, the answer is 0 * 0 = 0.
+
+Example 3:
+Input: s = "9876543210", queries = [[0,9]]
+Output: [444444137]
+Explanation:
+s[0..9] = "9876543210"
+x = 987654321
+sum = 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 45
+Therefore, the answer is 987654321 * 45 = 44444444445.
+We return 44444444445 modulo (109 + 7) = 444444137.
+
+Constraints:
+1 <= m == s.length <= 1^05
+s consists of digits only.
+1 <= queries.length <= 10^5
+queries[i] = [li, ri]
+0 <= li <= ri < m
+*/
+
+#include <iostream>
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <numeric>
+#include <cmath>
+#include <queue>
+#include <stack>
+#include <set>
+#include <map>
+#include <unordered_map>
+#include <unordered_set>
+#include <sstream>
+#include <limits>
+#include <iomanip>
+#include <functional>
+#include <cstring>
+#include <climits>
+#include "../core/core.h"
+using namespace std;
+
+const int mod = 1e9 + 7;
+const int maxN = 100001;
+long long pow10[maxN];
+
+int init = []()
+    {
+        pow10[0] = 1;
+        for (int i = 1; i < maxN; i++)
+        {
+            pow10[i] = (pow10[i - 1] * 10) % mod;
+        }
+        return 0;
+    }();
+
+class Solution
+{
+public:
+    vector<int> sumAndMultiply(string s, vector<vector<int>>& queries)
+    {
+        int n = s.size();
+        vector<int> sum(n + 1, 0);
+        vector<long long> x(n + 1, 0);
+        vector<int> count(n + 1, 0);
+        for (int i = 0; i < n; i++)
+        {
+            int d = s[i] - '0';
+            sum[i + 1] = sum[i] + d;
+            x[i + 1] = (d > 0) ? (x[i] * 10 + d) % mod : x[i];
+            count[i + 1] = count[i] + (d > 0);
+        }
+        int m = queries.size();
+        vector<int> result(m, 0);
+        for (int i = 0; i < m; i++)
+        {
+            int l = queries[i][0];
+            int r = queries[i][1] + 1;
+            int length = count[r] - count[l];
+            long long valX = (x[r] - x[l] * pow10[length] % mod + mod) % mod;
+            long long valSum = sum[r] - sum[l];
+            result[i] = (valX * valSum) % mod;
+        }
+
+        return result;
+    }
+};
+
+int main()
+{
+    int m;
+    string s;
+    cin >> s >> m;
+    vector<vector<int>> queries(m, vector<int>(2, 0));
+    for (int i = 0; i < m; i++)
+    {
+        cin >> queries[i][0] >> queries[i][1];
+    }
+    Solution sol;
+    vector<int> result = sol.sumAndMultiply(s, queries);
+    Core::printVectorResult(result);
+	return 0;
+}

tests/3700-3799/3756.txt

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+Test Case 1:
+Input:
+10203004
+3
+0 7
+1 3
+4 6
+Output:
+12340 4 9
+
+Test Case 2:
+Input:
+1000
+2
+0 3
+1 1
+Output:
+1 0
+
+Test Case 3:
+Input:
+9876543210
+1
+0 9
+Output:
+444444137