读完题感觉就是一01背包,仔细想想确又没什么好的思路,感觉只能暴力水水... 看了下discuss里讨论的,写了第一个代码
#include<cstdio>
#include<cstring>
using namespace std ;
int heg[21] ;
bool f[20000001] ;
int main(){
int n, h, i, j ;
while(~scanf("%d%d", &n, &h)){
int sum = 0 ;
int min = 200000000 ;
for(i=0; i<n; i++){
scanf("%d", &heg[i]) ;
sum += heg[i] ;
}
memset(f, 0, sizeof(f)) ;
f[0] = 1 ;
for(i=0; i<n; i++)
for(j=sum-heg[i]; j>=0; j--){
if(f[j]){
f[j+heg[i]] = 1 ;
if(j+heg[i]<min&&j+heg[i]>=h)
min = j+heg[i] ;
}
}
printf("%d\n", min-h) ;
}
return 0 ;
#include<cstring>
using namespace std ;
int heg[21] ;
bool f[20000001] ;
int main(){
int n, h, i, j ;
while(~scanf("%d%d", &n, &h)){
int sum = 0 ;
int min = 200000000 ;
for(i=0; i<n; i++){
scanf("%d", &heg[i]) ;
sum += heg[i] ;
}
memset(f, 0, sizeof(f)) ;
f[0] = 1 ;
for(i=0; i<n; i++)
for(j=sum-heg[i]; j>=0; j--){
if(f[j]){
f[j+heg[i]] = 1 ;
if(j+heg[i]<min&&j+heg[i]>=h)
min = j+heg[i] ;
}
}
printf("%d\n", min-h) ;
}
return 0 ;
}
后来跟xsy纠结了好一会把暴力的给写出来了,让我纳闷的是如果将DP[]全部初始化就会MLE ,动态初始化就OK,看来还是太水了,poj数据也是太水了...
#include<cstdio>
#include<cstring>
#define max(a, b) a>b?a:b
using namespace std ;
int dp[20000001] ;
int heg[21] ;
int main(){
int n, h, i, j ;
while(~scanf("%d%d", &n, &h)){
int sum = 0 ;
int min = 9999999 ;
for(i=0; i<n; i++){
scanf("%d", &heg[i]) ;
sum += heg[i] ;
}
for(i=0; i<=sum; i++)
dp[i] = 0 ;
for(i=0; i<n; i++)
for(j=sum; j>=heg[i]; j--){
dp[j] = max(dp[j], dp[j-heg[i]]+heg[i]) ;
if(dp[j]>=h&&dp[j]-h<min)
min = dp[j]-h ;
}
printf("%d\n", min) ;
}
return 0 ;
#include<cstring>
#define max(a, b) a>b?a:b
using namespace std ;
int dp[20000001] ;
int heg[21] ;
int main(){
int n, h, i, j ;
while(~scanf("%d%d", &n, &h)){
int sum = 0 ;
int min = 9999999 ;
for(i=0; i<n; i++){
scanf("%d", &heg[i]) ;
sum += heg[i] ;
}
for(i=0; i<=sum; i++)
dp[i] = 0 ;
for(i=0; i<n; i++)
for(j=sum; j>=heg[i]; j--){
dp[j] = max(dp[j], dp[j-heg[i]]+heg[i]) ;
if(dp[j]>=h&&dp[j]-h<min)
min = dp[j]-h ;
}
printf("%d\n", min) ;
}
return 0 ;
}
提交运行后发现我们写的比参考别人的第一段代码运行的还要快...没道理啊。
最后用DFS过了一下
#include<cstdio>
#include<cstring>
using namespace std ;
int heg[21] ;
int n, h, ans ;
void dfs(int dep, int sh){
if(sh>=ans)
return ;
if(dep==n){
if(sh>=h) ans = sh ;
return ;
}
dfs(dep+1, sh+heg[dep]) ;
dfs(dep+1, sh) ;
}
int main(){
int i ;
while(~scanf("%d%d", &n, &h)){
for(i=0; i<n; i++)
scanf("%d", &heg[i]) ;
ans = 9999999 ;
dfs(0, 0) ;
printf("%d\n", ans-h) ;
}
return 0 ;
#include<cstring>
using namespace std ;
int heg[21] ;
int n, h, ans ;
void dfs(int dep, int sh){
if(sh>=ans)
return ;
if(dep==n){
if(sh>=h) ans = sh ;
return ;
}
dfs(dep+1, sh+heg[dep]) ;
dfs(dep+1, sh) ;
}
int main(){
int i ;
while(~scanf("%d%d", &n, &h)){
for(i=0; i<n; i++)
scanf("%d", &heg[i]) ;
ans = 9999999 ;
dfs(0, 0) ;
printf("%d\n", ans-h) ;
}
return 0 ;
}