codeforces 303 D. Ilya and Roads(动态规划)

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多年没有写动态规划就是个悲剧啊!!省赛结束之后学习数据结构+动态规划..努力努力

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <cmath>#include <stack>#include <map>#include <string>#define LL long long#define DB doubleusing namespace std;const int N = 509;const int M = 100009;LL dp[N][N];struct LT{    int to,dis,nex;} L[M];int F[N],cnt =1 ;void add(int f,int t,int d){    L[cnt].dis = d; L[cnt].nex = F[f];    L[cnt].to = t; F[f] = cnt++;}int n,m,k;const int INF = 0x3f3f3f3f;void solve(){    for(int i=0;i<=n+1;i++)    {        for(int j=1;j<=n+1;j++)        dp[i][j] = 1ll*INF*INF;    }    for(int i=0;i<=n;i++)    {        for(int j=n;j>0;j--)            dp[i][j] = min(dp[i][j],dp[i][j+1]);        for(int j=0;j<=n;j++)        {            if(i-1>=0)            dp[i][j] = min(dp[i-1][j],dp[i][j]);            for(int k=F[i];k;k=L[k].nex)            {                int to = L[k].to;                if(j+(to-i)<=n)                {                    dp[to][j+(to-i)] = min(dp[to][j+(to-i)],dp[i][j]+L[k].dis);                }            }        }    }    LL ans = 1ll*INF*INF;    for(int i=1;i<=n;i++)    {        for(int j=k;j<=n;j++)        ans = min(dp[i][j],ans);    }    if(ans==1ll*INF*INF) cout<<"-1"<<endl;    else cout<<ans<<endl;}int re[N][N];int main(){    #ifndef ONLINE_JUDGE    freopen("in.txt","r",stdin);    #endif    int a,b,c;    scanf("%d%d%d",&n,&m,&k);    cnt = 1;    memset(re,0x7f,sizeof(re));    for(int i=0;i<m;i++)    {        scanf("%d%d%d",&a,&b,&c);        for(int j=a;j<=b;j++)        re[j][b] = min(re[j][b],c);    }    for(int i=1;i<=n;i++)    for(int j=i;j<=n;j++)    if(re[i][j]!=0x7f7f7f7f)    {        add(i-1,j,re[i][j]);    }    solve();    return 0;}