P1280 尼克的任务

题面:https://www.luogu.org/problem/P1280

本题唯一需要注意的是要倒序枚举,因为若正序枚举的话,在转移i的时候还没有转移i+t,所以只能倒序转移.

Code:
#include<iostream>
#include<cstdlib>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=10005;
int n,k,sum[N],f[N];
struct Node{
    int st,last;  
}work[N];  
int cmp(Node a,Node b){ 
    return a.st>b.st;  
}
int main() {
    long int i,j;   
    scanf("%d%d",&n,&k);
    for(i=1;i<=k;i++){
		scanf("%d%d",&work[i].st,&work[i].last);
		sum[work[i].st]++;
    }  
    sort(work+1,work+1+k,cmp);
	int num=1;
    for(i=n;i>=1;i--){
        if(sum[i]==0){
			f[i]=f[i+1]+1;
		}
        else{
			for(j=1;j<=sum[i];j++){
				if(f[i+work[num].last]>f[i]){
					f[i]=f[i+work[num].last];
				}
				num++;
			}
		}
    }
    printf("%d\n",f[1]);
	return 0;
}