【DP】 HDOJ 4960 Another OCD Patient

来源：互联网发布：百度霸屏js跳转代码编辑：程序博客网时间：2024/06/05 08:14

从两端往中间合并。。。合并过程中的数必然向数小的一方先合并。。。然后我们就可以这样先预处理出关节点。。。然后再关节点上一维DP即可。。。。

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>  #include <cstdlib>#include <cmath>#include <time.h>#define maxn 5005#define maxm 40005#define eps 1e-10#define mod 1000000007#define INF 999999999#define lowbit(x) (x&(-x))#define mp mark_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R  typedef long long LL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}// headint cost[maxn], num[maxn];int hash[maxn];int p[maxn];int dp[maxn];int n, cnt;void init(void){cnt = 0;memset(dp, -1, sizeof dp);}void read(void){for(int i = 1; i <= n; i++) scanf("%d", &num[i]);for(int i = 1; i <= n; i++) scanf("%d", &cost[i]);}int dfs(int now){if(~dp[now]) return dp[now];int x = p[now], y = hash[x];if(y - x - 1 > 0) dp[now] = cost[y - x - 1];else dp[now] = 0;for(int i = now+1; i <= cnt; i++) {int xx = p[i], yy = hash[xx];dp[now] = min(dp[now], dfs(i) + cost[xx - x] + cost[y - yy]);}return dp[now];}void work(void){int i = 0, j = n+1;p[++cnt] = 0, hash[0] = n+1;LL a = 0, b = 0;while(i < j) {if(a <= b) a += num[++i];else b += num[--j];if(a == b) hash[i] = j, p[++cnt] = i;}if(p[cnt] == hash[p[cnt]]) --cnt;printf("%d\n", dfs(1));}int main(void){while(scanf("%d", &n), n != 0) {init();read();work();}return 0;}

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