Uvs: 10487

Question: 10487-Closest Sums

Give a group of data, and then give m query numbers. It is required to find the sum of the two data in this group and the data closest to this query, and output the sum of the two data.

Solution: Perform binary search. If this is found, the query value is output, but note that the query cannot be found: the closest value here is not necessarily the previous data at the time when it cannot be found, so maintain the value of the nearest number to be queried.

Code:

#include <stdio.h>#include <algorithm>#include <stdlib.h>using namespace std;const int N = 1005;int s[N];int n, q;int min (const int a, const int b) {if (a == 0)return b;return abs(a - q) < abs (b - q)? a: b;}int search () {int l = 0;int r = n - 1;int sum = 0;while (l <= n - 1 && r >= 0 && l < r) {if (s[l] + s[r] < q) {sum = min (sum, s[l] + s[r]);l++;}else if (s[l] + s[r] > q) {sum = min (sum , s[l] + s[r]);r--;}elsereturn s[l] + s[r]; }return sum;}int main () {int m;int t = 0;while (scanf ("%d", &n), n) {for (int i = 0; i < n; i++)scanf ("%d", &s[i]);sort (s, s + n);scanf ("%d", &m);printf ("Case %d:\n", ++t);for (int i = 0; i < m; i++) {scanf ("%d", &q);printf ("Closest sum to %d is %d.\n", q, search ());}}return 0;}