题目链接:传送门
题意:有m个区间,你选k个使得所选的总区间最大。
思路: dp[r][k] 表示以r为结尾选k个区间的最大值。
ac代码:
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <string>
#include <cstring>
using namespace std;
typedef long long ll;
const ll mx = 2e3+100;
const ll mod = 1e9+7;
int dp[mx][mx], R[mx];
int main() {
int n, m, q, x, y, k;
scanf("%d", &q);
for (int i = 1; i <= q; ++i) {
printf("Case #%d: ", i);
scanf("%d%d%d", &n, &m, &k);
memset(dp, 0, sizeof(dp));
memset(R, 0, sizeof(R));
int l = 0, mxx = 0, r = 0;
for (int i = 0; i < m; ++i) {
scanf("%d%d", &l, &r);
for (; l <= r; ++l) R[l] = max(R[l], r);
}
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= k; ++j) {
dp[i][j] = max(dp[i-1][j], dp[i][j]);
if (R[i]) {
dp[R[i]][j] = max(dp[R[i]][j], dp[i-1][j-1]+R[i]-i+1);
}
}
}
printf("%d\n", dp[n][k]);
}
return 0;
}