poj 1821 分类： poj 2015-08-10 15:37 5人阅读 评论(0) 收藏

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把转移方程优化一下，改变决策顺序就行了。。。

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#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <string>
#include <map>
#include <vector>
#include <stack>
#include <queue>
#include <utility>
#include <iostream>
#include <algorithm>

template<class Num>void read(Num &x)
{
    char c; int flag = 1;
    while((c = getchar()) < '0' || c > '9')
        if(c == '-') flag *= -1;
    x = c - '0';
    while((c = getchar()) >= '0' && c <= '9')
        x = (x<<3) + (x<<1) + (c-'0');
    x *= flag;
    return;
}
template<class Num>void write(Num x)
{
    if(x < 0) putchar('-'), x = -x;
    static char s[20];int sl = 0;
    while(x) s[sl++] = x%10 + '0',x /= 10;
    if(!sl) {putchar('0');return;}
    while(sl) putchar(s[--sl]);
}

#define REP(__i,__st,__ed) for(int __i = (__st); __i <= (__ed); __i++)
#define _REP(__i,__st,__ed) for(int __i = (__st); __i >= (__ed); __i--)
const int maxn = 1e5 + 50, maxk = 105;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;

struct type_worker 
{
    int L, P, S;

    void scan()
    {
        read(L), read(P), read(S);
    }

}wk[maxk];

bool cmp(const type_worker &a, const type_worker &b)
{
    return a.S < b.S;
}

int N, K;
long long dp[maxk][maxn];

#define calc(x, y) (dp[x - 1][y] - (y)*wk[x].P)

long long solve()
{
//  f[i][j] = f[i-1][k] + (j - k)*P[i] = (f[i-1][k] - k*P[i]) + j*P[i]
// 0 <= j - k < Li     j - Li <= k < Si <= j 

    for(int i = 1; i <= K; i++)
    {
        long long maxv = -LINF;

        for(int p = std::max(std::min(wk[i].S + wk[i].L - 1, N) - wk[i].L, 0); p < wk[i].S; p++) maxv = std::max(maxv, calc(i, p));

        for(int j = std::min(wk[i].S + wk[i].L - 1, N); j >= wk[i].S ; j--)
        {
            if(j - wk[i].L >= 0) maxv = std::max(maxv, calc(i, j - wk[i].L));

            dp[i][j] = std::max(0LL, maxv + j*wk[i].P);
        }

        for(int j = 1; j <= N; j++)
            dp[i][j] = std::max(dp[i][j], std::max(dp[i - 1][j], dp[i][j - 1]));
    }

    return dp[K][N];
}
void init()
{
    read(N), read(K);

    REP(i, 1, K) wk[i].scan();

    std::sort(wk + 1, wk + K + 1, cmp);
}
int main()
{
#ifndef ONLINE_JUDGE
    freopen("1821.in","r",stdin);
    freopen("1821.out","w",stdout);
#endif

    init(), write(solve());

#ifndef ONLINE_JUDGE
    fclose(stdin);
    fclose(stdout);
#endif
    return 0;           
}

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