reference:http://blog.csdn.net/zwj1452267376/article/details/50660202
Bound Found
Time Limit: 5000MS | Memory Limit: 65536K | |||
Total Submissions: 3401 | Accepted: 1049 | Special Judge |
Description
Signals of most probably extra-terrestrial origin have been received and digitalized by The Aeronautic and Space Administration (that must be going through a defiant phase: "But I want to use feet, not meters!"). Each signal seems to come in two parts: a sequence
of n integer values and a non-negative integer t. We'll not go into details, but researchers found out that a signal encodes two integer values. These can be found as the lower and upper bound of a subrange of the sequence whose absolute value of its sum is
closest to t.
You are given the sequence of n integers and the non-negative target t. You are to find a non-empty range of the sequence (i.e. a continuous subsequence) and output its lower index l and its upper index u. The absolute value of the sum of the values of the sequence from the l-th to the u-th element (inclusive) must be at least as close to t as the absolute value of the sum of any other non-empty range.
You are given the sequence of n integers and the non-negative target t. You are to find a non-empty range of the sequence (i.e. a continuous subsequence) and output its lower index l and its upper index u. The absolute value of the sum of the values of the sequence from the l-th to the u-th element (inclusive) must be at least as close to t as the absolute value of the sum of any other non-empty range.
Input
The input file contains several test cases. Each test case starts with two numbers n and k. Input is terminated by n=k=0. Otherwise, 1<=n<=100000 and there follow n integers with absolute values <=10000 which constitute the sequence. Then follow k queries for
this sequence. Each query is a target t with 0<=t<=1000000000.
Output
For each query output 3 numbers on a line: some closest absolute sum and the lower and upper indices of some range where this absolute sum is achieved. Possible indices start with 1 and go up to n.
Sample Input
5 1 -10 -5 0 5 10 3 10 2 -9 8 -7 6 -5 4 -3 2 -1 0 5 11 15 2 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 15 100 0 0
Sample Output
5 4 4 5 2 8 9 1 1 15 1 15 15 1 15
Source
题意:找出一段连续区间,他们的和的绝对值与t最接近。思路:计算前缀和后,小到大排序,这样就可以保证计算每段区间和时是正数,然后尺取。
# include <iostream> # include <cstring> # include <cstdio> # include <cmath> # include <algorithm> # define MAXN 100000 # define INF 0x3f3f3f3f using namespace std; struct node { int x, id; }a[MAXN+3]; bool cmp(node a, node b) { return a.x < b.x; } int main() { int n, k, t, l, r, ans, tmp, al, ar; while(~scanf("%d%d",&n,&k),n+k) { a[0].x = a[0].id = 0; for(int i=1; i<=n; ++i) { a[i].id = i; scanf("%d",&a[i].x); a[i].x += a[i-1].x; } sort(a, a+n+1, cmp); while(k--) { scanf("%d",&t); int l=0, r=1, ans, eps = INF; while(r <= n) { tmp = a[r].x - a[l].x; if(abs(t - tmp) < eps) { eps = abs(t - tmp); ans = tmp; al = min(a[l].id, a[r].id) + 1; ar = max(a[l].id, a[r].id); } if(tmp > t) ++l; else if(tmp < t) ++r; else break; if(r==l) ++r; } printf("%d %d %d\n",ans, al, ar); } } return 0; }