POJ - 3616 Milking Time(DAG)

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题目大意：给出N头牛的产奶时间段和产奶量，每接完一头牛的奶后，需要休息R分钟
问如何选择牛，才能使接到的产奶量达到最大

解题思路：DAG，按产奶的结束时间大小排序

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 1010;struct Interval{    int start, end, val;}inter[N];int n, m, r;int dp[N];bool cmp(const Interval &a, const Interval &b) {    return a.end < b.end;}void init() {    for (int i = 0; i < n; i++)        scanf("%d%d%d", &inter[i].start, &inter[i].end, &inter[i].val);    sort(inter, inter + n, cmp);}void solve() {    for (int i = 0; i < n; i++)        dp[i] = inter[i].val;    for (int i = 0; i < n; i++)        for (int j = 0; j < i; j++)            if (inter[i].start >= inter[j].end + r)                dp[i] = max(dp[i], dp[j] + inter[i].val);    int ans = 0;    for (int i = 0; i < n; i++)        ans = max(ans, dp[i]);    printf("%d\n", ans);}int main() {    while (scanf("%d%d%d", &m, &n, &r) != EOF) {        init();        solve();    }    return 0;}

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