USACO 2.3 Zero Sum
TASK: zerosum
LANG: C++
Compiling...
Compile: OK
Executing...
Test 1: TEST OK [0.000 secs, 3028 KB]
Test 2: TEST OK [0.000 secs, 3028 KB]
Test 3: TEST OK [0.000 secs, 3028 KB]
Test 4: TEST OK [0.000 secs, 3028 KB]
Test 5: TEST OK [0.000 secs, 3028 KB]
Test 6: TEST OK [0.000 secs, 3028 KB]
Test 7: TEST OK [0.000 secs, 3028 KB]
All tests OK.
1 /*
2 PROG: zerosum
3 ID: jiafeim1
4 LANG: C++
5 */
6
7 #include <algorithm>
8 #include <iostream>
9 #include <fstream>
10
11 using namespace std;
12
13 char res[13] = {0};
14 int top=1;
15 long value = 0;
16 int n ;
17 std::ofstream fout("zerosum.out");
18 void output()
19 {
20 for(int i=1;i<=n-1;++i)
21 {
22 fout<<i<<res[i];
23 }
24 fout<<n<<endl;
25 }
26
27 void work(long num,long last_num,char last_mark)
28 {
29 if(num == n)
30 {
31 if(res[num-1] == ' ')
32 {
33 last_num = last_num*10+num;
34 }
35 else
36 {
37 last_num = num;
38
39 }
40 if(last_mark == '+' && value + last_num== 0)
41 output();
42 if(last_mark == '-' && value - last_num == 0)
43 output();
44 }
45 else
46 {
47 if(res[num-1] == ' ')
48 last_num = last_num*10 +num;
49
50
51 res[top++] = ' ';
52 if(res[num-1] == ' ')
53 work(num+1,last_num,last_mark);
54 else
55 work(num+1,num,last_mark);
56 --top;
57 int temp_value = value;
58 if(res[num-1] == ' ' || last_mark == ' ')
59 {
60 if(last_mark == '+')
61 value +=last_num;
62 if(last_mark == '-')
63 value -=last_num;
64 if(last_mark == ' ')
65 value = last_num;
66 }
67 else
68 {
69 if(last_mark == '+')
70 value +=num;
71 if(last_mark == '-')
72 value -=num;
73 last_num = num;
74 }
75 res[top++]='+';
76 work(num+1,last_num,'+');
77 --top;
78 res[top++]='-';
79 work(num+1,last_num,'-');
80 --top;
81 value = temp_value;
82 }
83 }
84 int main()
85 {
86 std::ifstream fin("zerosum.in");
87 res[0] = ' ';
88
89 fin>>n;
90 work(1,0,' ');
91
92 fin.close();
93 fout.close();
94
95 }
