HDU 2143 Can you find it?(基礎二分)
阿新 • • 發佈:2018-08-24
i++ php http miss then represent ise for stream
Input
There are many cases. Every data case is described as followed: In the first line there are three integers L, N, M, in the second line there are L integers represent the sequence A, in the third line there are N integers represent the sequences B, in the forth line there are M integers represent the sequence C. In the fifth line there is an integer S represents there are S integers X to be calculated. 1<=L, N, M<=500, 1<=S<=1000. all the integers are 32-integers.
Output
For each case, firstly you have to print the case number as the form "Case d:", then for the S queries, you calculate if the formula can be satisfied or not. If satisfied, you print "YES", otherwise print "NO".
Author
wangye
Can you find it?
Time Limit: 10000/3000 MS (Java/Others) Memory Limit: 32768/10000 K (Java/Others)
Total Submission(s): 42520 Accepted Submission(s): 10315
Sample Input 3 3 3 1 2 3 1 2 3 1 2 3 3 1 4 10
Sample Output Case 1: NO YES NO
Source HDU 2007-11 Programming Contest
Recommend 威士忌 | We have carefully selected several similar problems for you: 2899 2289 1597 1551 2298 今天從基礎開始學起,以為二分挺容易的,但是忽視了題目需要考慮時間復雜度,會不會爆int,等等。 存不存在ai,bi,ci加起來是x。 如果直接枚舉那也太簡單了吧,我就想著,大循環a,小循環b,小小循環對c二分,發現這樣也超時!!! 然後,我就大循環a,小循環對b二分,小小循環對c二分,結果這樣的思路是完全錯的!!! 然後看看題解,要先把a+b的所有可能都存起來放到sum裏,再大循環c,對sum二分。開始還覺得這個思路不是和我一開始的思路差不多嗎?仔細一想,我大循環a,小循環b,一方面會有很多重復的a+b,重復帶入算,費時,另一方面,每輸入一個x,又要大循環啊,小循環b的,很費時。
#include <iostream> #include <stack> #include <string.h> #include <stdio.h> #include<queue> #include<algorithm> #define ll long long using namespace std; int a[505]; int b[505]; int c[505]; int sum[500005]; int main() { int L,N,M; int k=0; while(~scanf("%d %d %d",&L,&N,&M)) { k++; for(int i=1;i<=L;i++) { scanf("%d",&a[i]); } for(int i=1;i<=N;i++) { scanf("%d",&b[i]); } for(int i=1;i<=M;i++) { scanf("%d",&c[i]); } int n,x; printf("Case %d:\n",k); scanf("%d",&n); int p=1; for(int i=1;i<=L;i++) { for(int j=1;j<=N;j++) { sum[p++]=a[i]+b[j]; } } sort(sum+1,sum+p); sort(c+1,c+1+M); while(n--) { scanf("%d",&x); bool f=0; for(int i=1;i<=M;i++) { if(sum[1]>x-c[i])//不能寫成sum[1]+c[1]>x,因為可能會爆int break; int le=1;int ri=p-1; while(le<=ri) { int mid=(le+ri)/2; if(sum[mid]==x-c[i]) { f=1; break; } else if(sum[mid]>x-c[i]) { ri=mid-1; } else if(sum[mid]<x-c[i]) le=mid+1; } if(f) break; } if(f) printf("YES\n"); else printf("NO\n"); } } return 0; }
HDU 2143 Can you find it?(基礎二分)