CodeForces 189A Cut Ribbon

题意:给出四个数n,a,b,c,将长度为n的木棍恰好分割成若干段长度分别为a,b,c的小段,求最多能有几段

链接:http://codeforces.com/problemset/problem/189/A

思路:dp,近似完全背包,加一个判断条件dp[i-k] != 0

注意点:无


以下为AC代码:

# Author Problem Lang Verdict Time Memory Sent Judged
10042577 Practice:
luminous11
189A - 38 GNU C++11 Accepted 62 ms 24 KB 2015-02-27 12:39:58 2015-02-27 12:39:58
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define ll long long
#define ull unsigned long long
#define all(x) (x).begin(), (x).end()
#define clr(a, v) memset( a , v , sizeof(a) )
#define pb push_back
#define mp make_pair
#define read(f) freopen(f, "r", stdin)
#define write(f) freopen(f, "w", stdout)
using namespace std;
const double pi = acos(-1);
//Problem A
int dp[5000];
int main()
{
    ios::sync_with_stdio( false );
    int n, a, b, c;
    while ( cin >> n >> a >> b >> c ){
        clr ( dp, 0 );
        dp[a] = dp[b] = dp[c] = 1;
        for ( int i = a; i <= n; i ++ ){
            if ( dp[i-a] )
                dp[i] = max ( dp[i], dp[i-a] + 1 );
        }
        for ( int i = b; i <= n; i ++ ){
            if ( dp[i-b] )
                dp[i] = max ( dp[i], dp[i-b] + 1 );
        }
        for ( int i = c; i <= n; i ++ ){
            if ( dp[i-c] )
                dp[i] = max ( dp[i], dp[i-c] + 1 );
        }
        cout << dp[n] << endl;
    }
    return 0;
}


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