【DP】 ZOJ 2561 Order-Preserving Codes

这个题和石子合并那个题没什么区别。。。四边形优化一下就可以了。。。

#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 2005#define maxm 1000005#define eps 1e-10#define mod 1000000007#define INF 1e17#define PI (acos(-1.0))#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid #define rson o<<1 | 1, mid+1, R#pragma comment(linker, "/STACK:16777216")typedef long long LL;typedef unsigned long long ULL;//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);}// headLL dp[maxn][maxn];int p[maxn], cnt;int s[maxn][maxn];LL sum[maxn];int a[maxn];int n;void read(void){for(int i = 1; i <= n; i++) scanf("%d", &a[i]);}void dfs(int L, int R, int k){if(L == R) {for(int i = 0; i < cnt; i++) printf("%d", p[i]);printf("\n");return;}p[cnt++] = 0;dfs(L, k, s[L][k]);p[cnt-1] = 1;dfs(k + 1, R, s[k+1][R]);cnt--;}void work(void){for(int i = 0; i <= n; i++)for(int j = 0; j <= n; j++)dp[i][j] = INF;for(int i = 1; i <= n; i++) sum[i] = sum[i-1] + a[i];for(int i = 1; i <= n; i++) dp[i][i] = sum[i] - sum[i-1], s[i][i] = i;for(int p = 1; p <= n; p++) {for(int i = 1; i + p <= n; i++) {int j = i + p;for(int k = s[i][j-1]; k <= s[i+1][j]; k++)if(dp[i][j] > dp[i][k] + dp[k+1][j] + sum[j] - sum[i-1]) {dp[i][j] = dp[i][k] + dp[k+1][j] + sum[j] - sum[i-1];s[i][j] = k;}}}dfs(1, n, s[1][n]);}int main(void){while(scanf("%d", &n) != EOF) {read();work();}return 0;}