普及练习场 贪心EX 皇后游戏

题目链接

题意理解

显然，第i+1 位大臣拿的钱比第i 位大臣多

记i−1位大臣拿的钱为ci−1 ，第i 位大臣和第i+1位大臣拿的钱可以分别表示出来。此时顺序是，i−1,i,i+1 ①

然后交换第i 位大臣和第i+1位大臣。此时顺序是i−1,i+1,i②

此时我们希望第i+1位大臣排在后面拿的钱要少与第i 位大臣排在后面的前，此时就有不等式了

代码

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;
class People implements Comparable{
int l;
int r;
public People(int l, int r) {
this.l = l;
this.r = r;
}
@Override
public int compareTo(Object o) {
People people = (People)o;
return Math.min(this.l, people.r) - Math.min(this.r, people.l);
}

}
public class Main {
static int T;
static int n;
static People[] peoples;
public static void main(String[] args) {
FastScanner fs = new FastScanner();
T = fs.nextInt();
while(T-->0) {
long sum = 0;
long[] dp = new long[50050];
dp[0] = 0;
n = fs.nextInt();
peoples = new People
;
for(int i = 0; i < n; i++) {
int x = fs.nextInt();
int y = fs.nextInt();
peoples[i] = new People(x, y);
}
Arrays.sort(peoples);
for(int i = 0; i < n; i++) {
sum += peoples[i].l;
dp[i] = Math.max(dp[Math.max(0, i - 1)], sum) + peoples[i].r;
}
System.out.println(dp[n-1]);
}
}
public static class FastScanner {
private BufferedReader br;
private StringTokenizer st;

public FastScanner() {
br = new BufferedReader(new InputStreamReader(System.in));
}

public String nextToken() {
while(st == null || !st.hasMoreElements()) {
try {
st = new StringTokenizer(br.readLine());
} catch (Exception e) {
// TODO: handle exception
}
}
return st.nextToken();
}

public int nextInt() {
return Integer.valueOf(nextToken());
}
}
}