UVa 10154 Weights and Measures DP

初始化DP数组各种WA，比人的初始memset(0x7f) 然后判断就直接<(1<<30)实在看不出有啥道理。

我自己开始是INT_MAX；然后后来判断就直接<INT_MAX.就各种WA了。

后来看下感觉这里递推时会加爆INT所以WA？所以要判断以前前面的状态是否存在,就DP[I-1][J-1]！=INT_MAX;

for (int i=1;i<=cas;i++)

for (int j=1;j<=i;j++)

{

dp[i][j]=min(dp[i][j],dp[i-1][j]);

if (dp[i-1][j-1]!=INT_MAX &&dp[i-1][j-1]+src[i].weight<=src[i].power )

dp[i][j]=min(dp[i][j],dp[i-1][j-1]+src[i].weight);

}

按照力量有小至大排序，dp[i][j]表示前i个乌龟中选j个乌龟的最小重量。

#include <map>
#include <set>
#include <list>
#include <cmath>
#include<cctype>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cstdio>
#include <string>
#include <vector>
#include<climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 5700
struct node
{
int weight,power;
friend bool operator < (const node &a,const node &b)
{
if (a.power==b.power) return a.weight<b.weight;
return a.power<b.power;
}
}src[MAXN];
int dp[MAXN][MAXN];
int Max,cas;
int main()
{
//freopen("sample.txt","r",stdin);
cas=1;
int a,b;
while (scanf("%d%d",&a,&b)!=EOF)
{
src[cas].weight=a;
src[cas].power=b;
cas++;
}
cas--;
sort(src+1,src+1+cas);
//for (int i=1;i<=cas;i++) printf("%d %d\n",src[i].power,src[i].weight);
for (int i = 0; i <= cas; ++i)
{
dp[i][0] = 0;
for (int j = 1; j <= cas; ++j)
dp[i][j] = INT_MAX;
}
for (int i=0;i<=cas;i++) dp[i][0]=0;
for (int i=1;i<=cas;i++)
for (int j=1;j<=i;j++)
{
dp[i][j]=min(dp[i][j],dp[i-1][j]);
if (dp[i-1][j-1]!=INT_MAX &&dp[i-1][j-1]+src[i].weight<=src[i].power  )
dp[i][j]=min(dp[i][j],dp[i-1][j-1]+src[i].weight);
}
int i;
//printf("%d\n",cas);
//for (int i=cas;i>0;i--) printf("dp[%d][%d]=%d\n",cas,i,dp[cas][i]);
//for ( i=cas-1;i>=0;i--) printf("%d ",dp[cas-1][i]);
for (i=cas;i>0;i--) if (dp[cas][i]<INT_MAX) break;
if (i)
printf("%d\n",i);
else puts("1");
return 0;
}