luogu P2134 百日旅行

题目链接

luogu P2134 百日旅行

题解

dp方程好想吧

优化有些玄学惹 不会证....

不过我会三分和贪心 \滑稽

但还是写dp吧

代码

#include<cstdio>
#include<cstring>
#include<algorithm>
inline int read() {
    int x = 0,f = 1;char c = getchar();
    while(c < '0' || c > '9') {if(c == '-') f = -1;c = getchar();}
    while(c <= '9' && c >= '0') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
const int maxn = 200007;
int q , p , g;
int n;
int  dp[maxn][2];

int main () {
    n = read(), p = read(), q = read();
    for(int i = 1;i <= n;++ i) {
        for(int j = g + 1;j < i;++ j)
            if(dp[g][1] + (i - g) * (i - g) * p > dp[j][1] + (i - j) * (i - j) * p)
g = j;
        dp[i][1] = std::min (dp[i - 1][1],dp[i - 1][0]) + q;
        dp[i][0] = dp[g][1] + (i - g) * (i - g) * p;
    }
    printf("%d\n",std::min(dp[n][0],dp[n][1]));
    return 0;
}