Nyoj 927 the partial sum problem (DFS)

Describe

 from  is equal to K.  

Input

 Case  is an integer n (1≤n≤), represents the array contains n integers. The second line contains N integers,the ith integer represents a[i] (-^8≤a[i]≤ ^8 ). The third line contains an integer K (-^8≤k≤ ^8).

Output

 from  is k,printf "of Course,i can!"; Other printf "Sorry,i can ' t!".

Sample input

4 1 2 4 7  - 4 1 2 4 7  the

Sample output

of Course,i can! Sorry,i can ' t!

Two methods:

The first kind of direct backtracking DFS

1 #pragmaComment (linker, "/stack:1024000000,1024000000")2#include <iostream>3#include <cstdio>4#include <cstring>5#include <cmath>6#include <math.h>7#include <algorithm>8#include <queue>9#include <Set>Ten#include <bitset> One#include <map> A#include <vector> -#include <stdlib.h> -#include <stack> the using namespacestd; - #definePI ACOs (-1.0) - #defineMax (a) (a) > (b)? (a): (b) - #defineMin (a) (a) < (b)? (a): (b) + #definell Long Long - #defineEPS 1e-10 + #defineMOD 1000000007 A #defineN 26 at #defineINF 1e12 - intN,m,flag; - intA[n]; - intVis[n]; - voidDfsintNowintnum) { -    if(num>=m) { in          if(num==L) { -flag=1; to          } +          return; -    } the     for(inti=now;i<n;i++){ *       if(!Vis[i]) { $vis[i]=1;Panax NotoginsengDFS (i+1, num+a[i]); -          if(flag) { the             return; +          } Avis[i]=0; the       } +    } - } $ intMain () $ { -     while(SCANF ("%d", &n) = =1){ -        for(intI=0; i<n;i++){ thescanf"%d",&a[i]); -       }Wuyiscanf"%d",&m); thememset (Vis,0,sizeof(Vis)); -flag=0; WuDfs0,0); -       if(flag) { Aboutprintf"of Course,i can!\n"); $}Else{ -printf"sorry,i can ' t!\n"); -       } -    } A     return 0; +}

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The second type of DFS like 01 backpack thought

1 #pragmaComment (linker, "/stack:1024000000,1024000000")2#include <iostream>3#include <cstdio>4#include <cstring>5#include <cmath>6#include <math.h>7#include <algorithm>8#include <queue>9#include <Set>Ten#include <bitset> One#include <map> A#include <vector> -#include <stdlib.h> -#include <stack> the using namespacestd; - #definePI ACOs (-1.0) - #defineMax (a) (a) > (b)? (a): (b) - #defineMin (a) (a) < (b)? (a): (b) + #definell Long Long - #defineEPS 1e-10 + #defineMOD 1000000007 A #defineN 26 at #defineINF 1e12 - intn,m; - intA[n]; - BOOLDfsintCurintnum) { -    if(num>=m) { -       if(num==L) { in          return true; -       } to       return false; +    } -    if(cur>=n)return false; the    if(Dfs (cur+1, Num+a[cur]))return true; *    returnDFS (cur+1, num); $ Panax Notoginseng } - intMain () the { +     while(SCANF ("%d", &n) = =1){ A        for(intI=0; i<n;i++){ thescanf"%d",&a[i]); +       } -scanf"%d",&m); $       if(Dfs (0,0)){ $printf"of Course,i can!\n"); -}Else{ -printf"sorry,i can ' t!\n"); the       } -    }Wuyi     return 0; the}

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Nyoj 927 the partial sum problem (DFS)