2013长沙现场赛A - Alice's Print Service

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题意：给你2n个数，b[i]表示不小于a[i]页数时的单价，问你印刷一定页数时，最便宜是多少钱。因为可以选择再刷多n页来改变单价从而改变总价格，所以要考虑的东西比较多。下面给代码。

#include<iostream>   #include<cstring>  #include<cstdio> #include<algorithm>#include<string>#include<queue>#include<cmath>#include<set>using namespace std;#define maxn 100005#define xx 1000000001int a[maxn], b[maxn], n, m;int binarysearch(int value)  {int left = 1, right = n, mid;while (left<right){mid = (left + right) >> 1;if (value>a[mid])left = mid + 1;else right = mid - 1;}if (a[left]<=value)return left;return left - 1;}int main() {int t;scanf("%d", &t);while (t--) {scanf("%d%d", &n, &m);for (int i = 1; i <= n; i++) {scanf("%d%d", &a[i], &b[i]);}for (int i = n - 1; i >= 1; i--) {if ((long long)a[i] * b[i]>(long long)a[i + 1] * b[i + 1]) {a[i] = a[i + 1];b[i] = b[i + 1];}}//因为后面的价格有可能会更便宜，所以进行以上操作a[0] = xx;b[0] = xx;a[n + 1] = xx;b[n + 1] = xx;for (int i = 0; i < m; i++) {int q;scanf("%d", &q);int index = binarysearch(q);//暴力明显会超时，套二分就可以了。long long x = min((long long)b[index] * q, (long long)b[index + 1] * a[index + 1]);printf("%lld\n", x);}}}

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