[hdu3631]背包或中途相遇法
暴力的背包：
1 #pragma comment(linker, "/STACK:10240000,10240000") 2 3 #include <iostream> 4 #include <cstdio> 5 #include <algorithm> 6 #include <cstdlib> 7 #include <cstring> 8 #include <map> 9 #include <queue> 10 #include <deque> 11 #include <cmath> 12 #include <vector> 13 #include <ctime> 14 #include <cctype> 15 #include <set> 16 17 using namespace std; 18 19 #define mem0(a) memset(a, 0, sizeof(a)) 20 #define lson l, m, rt << 1 21 #define rson m + 1, r, rt << 1 | 1 22 #define define_m int m = (l + r) >> 1 23 #define rep(a, b) for(int a = 0; a < b; a++) 24 #define all(a) (a).begin(), (a).end() 25 #define lowbit(x) ((x) & (-(x))) 26 #define constructInt4(name, a, b, c, d) name(int a = 0, int b = 0, int c = 0, int d = 0): a(a), b(b), c(c), d(d) {} 27 #define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {} 28 #define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {} 29 #define pc(a) putchar(a) 30 #define ps(a) printf("%s", a) 31 #define pd(a) printf("%d", a) 32 #define sd(a) scanf("%d", &a) 33 34 typedef double db; 35 typedef long long LL; 36 typedef pair<int, int> pii; 37 typedef multiset<int> msi; 38 typedef set<int> si; 39 typedef vector<int> vi; 40 typedef map<int, int> mii; 41 42 const int dx[8] = {0, 1, 0, -1, 1, 1, -1, -1}; 43 const int dy[8] = {1, 0, -1, 0, -1, 1, 1, -1}; 44 const int maxn = 1e5 + 7; 45 const int maxm = 1e5 + 7; 46 const int maxv = 1e7 + 7; 47 const int max_val = 1e6 + 7; 48 const int MD = 1e9 +7; 49 const int INF = 1e9 + 7; 50 const double PI = acos(-1.0); 51 const double eps = 1e-10; 52 53 template<class T> T gcd(T a, T b) { return b == 0? a : gcd(b, a % b); } 54 55 int t, sum[33], a[33]; 56 bool f[10000007]; 57 int main() { 58 //freopen("in.txt", "r", stdin); 59 int n; 60 while (cin >> n >> t) { 61 rep(i, n) sd(a[i]); 62 sort(a, a + n); 63 sum[0] = a[0]; 64 rep(i, n - 1) sum[i + 1] = sum[i] + a[i + 1]; 65 mem0(f); 66 f[0] = true; 67 rep(i, n) { 68 int maxt = min(t, sum[i]); 69 for (int j = maxt; j >= a[i]; j--) { 70 f[j] = f[j] || f[j - a[i]]; 71 } 72 } 73 int ans; 74 for (int i = t; i >= 0; i--) { 75 if (f[i]) { 76 ans = i; 77 break; 78 } 79 } 80 cout << ans << endl; 81 } 82 return 0; 83 }
