POJ 1337 A Lazy Worker

Description

Summary:

1. Fill dp array explicitly by using dp[i] = dp[i+1]

2. At time i, do the first job explicitly

Code:

/*
 * source.cpp
 *
 *  Created on: Apr 5, 2014
 *      Author: sangs
 */

#include <iostream>
#include <stdio.h>
#include <set>
#include <memory.h>
#include <vector>
using namespace std;

class Job {
public:
	int st, ed, duration;
	Job(int _st, int _ed, int _du):st(_st), ed(_ed), duration(_du) {}
	Job() {
		st = ed = duration = 0;
	}
};

vector<Job> jobs[2500];
int dp[2500];

int cal(int n) {
	memset(dp, 0, sizeof(dp));
	for(int i = n; i >= 0; i --) {
		if(jobs[i].size() == 0) {
			dp[i] = dp[i+1];
			continue;
		}

		int du = jobs[i][0].duration;
		dp[i] = du + dp[i+du];

		for(size_t j = 1; j < jobs[i].size(); j ++) {
			du = jobs[i][j].duration;
			dp[i] = min(dp[i], du+dp[i+du]);
		}
	}

	for(int i = 0; i <= n; i ++)
		jobs[i].clear();

	return dp[0];
}

int main() {
	freopen("input.txt", "r", stdin);
	int cases, m;
	scanf("%d", &cases);

	while(cases --) {
		scanf("%d", &m);
		int n = 0;

		for(int i = 0; i < m; i ++) {
			int st, ed, du;
			scanf("%d%d%d", &du, &st, &ed);
			n = max(n, ed);
			for(int j = st; j <= ed-du; j ++) {
				jobs[j].push_back(Job(st, ed, du));
			}
		}
		int res = cal(n);
		printf("%d
", res);
	}

	return 0;
}