！ HDU 1243 Counter-terrorism training camp--dp--(longest common sub-sequence)

Test instructions: give you a bullet sequence and a terrorist sequence, only the bullets hit the corresponding serial number of terrorists to score, each terrorist has a corresponding score, to seek the maximum score

Analysis: The abstract model is the longest common sub-sequence, the direct set of formula: Dp[i][j] for the first time to hit J terrorist with the maximum score, note that this refers to the process from the starting state to the optimal solution, rather than the optimal solution of this state; State transfer: 1. When a[i ]==B[J], Dp[i][j]=dp[i-1][j-1]+v,v is the score of the terrorist b[j]; 2. Otherwise, Dp[i][j]=max (Dp[i-1][j-1],dp[i-1][j],dp[i][j-1])

Note:each time the 1.DP array is saved is the optimal solution of the process from the start state to the current state, not the optimal solution of this state; Remember that DP is a process, not an instantaneous one .

The error occurred in this question: 1. RE. The question did not say the data range I guess 1000, and later found it should be 2000; but I made a stupid mistake is I set the dp[1000][1000], should not be dp[1005][1005] it!

2.TLE. There are two reasons, one is the state transfer did not understand the middle once wrote a triple cycle; second, the problem can not be used memset, the use of the time-out.

3.MLE. The original is I for fear of WA, set a long long dp[][], the result is changed to int dp[][] on the line

Remember these few wonderful reasons for the wrong!

Code:

#include <iostream> #include <algorithm> #include <cstring> #include <string> #define INF 1000000007using namespace Std;int n,sc[200];int dp[2007][2007];string a,b;char c[10000];int n1,n2;int max (int p,int q) { C0/>return P>q?p:q;} void DP () {for    (int i=0;i<=n1;i++) dp[i][0]=0;    for (int j=0;j<=n2;j++) dp[0][j]=0;    for (int i=1;i<=n1;i++) {for        (int j=1;j<=n2;j++) {            if (a[i-1]==b[j-1])               dp[i][j]=dp[i-1][j-1]+sc[a[ I-1]];            Else Dp[i][j]=max (Dp[i-1][j-1],max (dp[i-1][j],dp[i][j-1));}}}            int main () {    int tmp;    while (Cin>>n) {for        (int i=0;i<200;i++) sc[i]=0;        for (int i=0;i<n;i++) cin>>c[i];        for (int i=0;i<n;i++) {            cin>>tmp;            sc[c[i]]=tmp;        }        cin>>a>>b;        N1=a.length ();        N2=b.length ();        DP ();        cout<<dp[n1][n2]<<endl;    }}

！ HDU 1243 Counter-terrorism training camp--dp--(longest common sub-sequence)