Description
Give you three sequences of numbers A, B, C, then we give you a number X. Now you need to calculate if you can find the three numbers Ai, Bj, Ck, which satisfy the formula Ai+Bj+Ck = X.
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".
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
解题思路:
首先我们考虑这个问题:给定两个序列A,B,和确定的数x,问是否存在i,j使满足A[i]+B[j]=x的?最快的方法是枚举A,然后在B中二分查找
x-A。现在回到这个问题,这道题给了三组序列A,B,C如何查找呢?我们不妨将A,C两数组合并成新数组LN,LN中每个元素都是Ai+Bj的和。然后枚举B,在LN中二分查找x-B。
*这里有个细节:由于x为32位整数,当A+B>INT32_MAX时,可以不用加入LN.
代码如下:
1 #include <iostream> 2 #include <cstdio> 3 #include <algorithm> 4 #include <time.h> 5 using namespace std; 6 #define clock__ printf("%f ",double(clock())/CLOCKS_PER_SEC); 7 #define maxn 500 8 #define INT_32_MAX ((1<<31)-1) 9 typedef long long LL; 10 int A[maxn+3],B[maxn+3],C[maxn+3]; 11 int L,M,N,S; 12 int LN[maxn*maxn+5]; 13 int h; 14 15 bool search_LN(int a,int b,int x){ 16 int len=b-a; 17 int mid=a+len/2; 18 if(len==1){ 19 if(LN[a]==x) return true; 20 else return false; 21 } 22 if(LN[mid]==x) return true; 23 else if(LN[mid]>x) return search_LN(a, mid, x); 24 else return search_LN(mid, b, x); 25 } 26 27 int main() { 28 29 int T=0; 30 while(scanf("%d%d%d",&L,&M,&N)==3){ 31 printf("Case %d: ",++T); 32 for(int i=0;i<L;i++) 33 scanf("%d",&A[i]); 34 for(int i=0;i<M;i++) 35 scanf("%d",&B[i]); 36 for(int i=0;i<N;i++) 37 scanf("%d",&C[i]); 38 h=0; 39 for(int i=0;i<L;i++) 40 for(int j=0;j<N;j++){ 41 if(LL(A[i])+C[j]<=INT_32_MAX) 42 LN[h++]=A[i]+C[j]; 43 } 44 sort(LN, LN+h); 45 scanf("%d",&S); 46 for(int i=1;i<=S;i++){ 47 int x; 48 scanf("%d",&x); 49 bool ok=0; 50 for(int j=0;!ok&&j<M;j++){ 51 if(search_LN(0,h, x-B[j])) 52 ok=1; 53 } 54 if(ok)printf("YES "); 55 else printf("NO "); 56 } 57 } 58 //clock__ 59 return 0; 60 }