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五、完善程序-1

序列合并) 有两个长度为 N 的单调不降序列 A 和 B,序列的每个元素都是小于 109 的非负整数。在 A 和 B 中各取一个数相加可以得到 N2 个和,求其中第 K 小的和。上述参数满足 N≤105 和 1≤K≤N2

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#include <iostream>
using namespace std;

const int maxn = 100005;

int n;
long long k;
int a[maxn], b[maxn];

int* upper_bound(int *a, int *an, int ai) {
    int l = 0, r = ___①___;
    while (l < r) {
        int mid = (l+r)>>1;
        if (___②___) {
            r = mid;
        } else {
            l = mid + 1;
        }
    }
    return ___③___;
}

long long get_rank(int sum) {
    long long rank = 0;
    for (int i = 0; i < n; ++i) {
        rank += upper_bound(b, b+n, sum - a[i]) - b;
    }
    return rank;
}

int solve() {
    int l = 0, r = ___④___;
    while (l < r) {
        int mid = ((long long)l+r)>>1;
        if (___⑤___) {
            l = mid + 1;
        } else {
            r = mid;
        }
    }
    return l;
}

int main() {
    cin >> n >> k;
    for (int i = 0; i < n; ++i) cin >> a[i];
    for (int i = 0; i < n; ++i) cin >> b[i];
    cout << solve() << endl;
}
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