P3040 [USACO12JAN]貝爾分享Bale Share
阿新 • • 發佈：2018-10-22
turn cin cas cst iostream read sse ++ 貝爾
想了一個二分 + 狀壓的思路, 嫌太麻煩了, 直接一個dfs + 最優性剪枝水了過去.
貌似比某些dp還快?
#include <cstdio> #include <cstring> #include <cassert> #include <iostream> #include <algorithm> using namespace std; const int MAXN = 20 + 2; inline int read(){ char ch = getchar(); int x = 0; while(!isdigit(ch)) ch = getchar(); while(isdigit(ch)) x = x * 10 + ch - '0', ch = getchar(); return x; } int N; int s[MAXN], sum; int ans = (1 << 30); void dfs(int u, int suma, int sumb, int sumc) { if(u == N + 1) return ans = min(ans, max(suma, max(sumb, sumc))), void(); if(suma + s[u] < ans) dfs(u + 1, suma + s[u], sumb, sumc); if(sumb + s[u] < ans) dfs(u + 1, suma, sumb + s[u], sumc); if(sumc + s[u] < ans) dfs(u + 1, suma, sumb, sumc + s[u]); return ; } int main(){ cin>>N; for(int i = 1; i <= N; i++) sum += (s[i] = read()); sort(s + 1, s + N + 1, greater<int>()); dfs(1, 0, 0, 0); printf("%d\n", ans); return 0; }
P3040 [USACO12JAN]貝爾分享Bale Share