添加 T637678 问题的完整解决方案，包括子集和计算和的实现

src/7/23/T637678.cpp

@@ -0,0 +1,73 @@
+#include <bits/stdc++.h>
+#include <cstdint>
+using namespace std;
+using ll = int64_t;
+
+vector<ll> sub(vector<int>& nums) {
+    int n = nums.size();
+    if (n == 0) {
+        return {0};
+    }
+    int tot = 1 << n;
+    vector<ll> res(tot, 0);
+    for (int i = 0; i < tot; i++) {
+        ll sum = 0;
+        for (int j = 0; j < n; j++) {
+            if (i & (1 << j)) {
+                sum += nums[j];
+            }
+        }
+        res[i] = sum;
+    }
+    return res;
+}
+
+int main() {
+    int n, q;
+    scanf("%d %d", &n, &q);
+    vector<int> v(n);
+    for (int i = 0; i < n; i++) {
+        scanf("%d", &v[i]);
+    }
+
+    int n1 = n / 2;
+    int n2 = n - n1;
+    vector<int> A, B;
+    for (int i = 0; i < n1; i++) 
+        A.push_back(v[i]);
+    for (int i = n1; i < n; i++)
+        B.push_back(v[i]);
+
+    vector<ll> sumA = sub(A);
+    vector<ll> sumB = sub(B);
+
+    sort(sumA.begin(), sumA.end());
+    sort(sumB.begin(), sumB.end());
+
+    int lenA = sumA.size();
+    int lenB = sumB.size();
+    ll maxB = lenB > 0 ? sumB[lenB - 1] : 0;
+
+    while (q--) {
+        ll l, r;
+        scanf("%lld %lld", &l, &r);
+        ll ans = 0;
+        int p = 0, q_idx = 0;
+        for (int i = lenA - 1; i >= 0; i--) {
+            ll a = sumA[i];
+            if (a < l - maxB) {
+                break;
+            }
+            ll L = l - a;
+            ll R = r - a;
+
+            while (p < lenB && sumB[p] < L)
+                p++;
+            while (q_idx < lenB && sumB[q_idx] <= R)
+                q_idx++;
+            ans += (q_idx - p);
+        }
+        printf("%lld\n", ans);
+    }
+    return 0;
+}