Codeforces 311B Cats Transport

来源：互联网发布：python开发web应用编辑：程序博客网时间：2024/04/29 01:03

第一次用斜率优化DP

用双端队列维护前一次的dp值。

代码：

#include<bits/stdc++.h>using namespace std;typedef long long ll;typedef pair<int, int> PII;const int N = 1e5+5;ll sum[N]{0}, a[N], dp[N], f[N];int Q[N];int main() {    int n, m, p, h;    cin >> n >> m >> p;    for(int i = 1; i < n; i++) { scanf("%lld", &f[i]); sum[i+1] = sum[i]+f[i];}    for(int i = 1; i <= m; i++) { scanf("%d%lld", &h, &a[i]); a[i] -= sum[h]; }    sort(a+1, a+m+1);    for(int i = m; i >= 1; i--) a[i] -= a[1];    for(int i = 1; i <= m; i++) {        sum[i] = sum[i-1]+a[i];        dp[i] = a[i]*i-sum[i];    }    for(int j = 1; j < p; j++) {        for(int i = 1; i <= m; i++) f[i] = dp[i]+sum[i];        int h = 0, t = -1;        for(int i = 1; i <= m; i++) {            while(h<t && (f[Q[h+1]]-f[Q[h]])<a[i]*(Q[h+1]-Q[h])) ++h;            while(h<t && (f[Q[t]]-f[Q[t-1]])*(i-Q[t])>(f[i]-f[Q[t]])*(Q[t]-Q[t-1])) --t;            Q[++t] = i;            dp[i] = f[Q[h]]+a[i]*(i-Q[h])-sum[i];        }    }    printf("%lld\n", dp[m]);    return 0;}

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