POJ 1661 help Jimmy (Memory search)

Title Link: http://poj.org/problem?id=1661

Also can be a memory search problem, mainly to think about how to set DP, memory search is to avoid recursive process of repeated evaluation, so to get DP must know how to recursion

Since this is a can move around the recursive process is definitely designed around so the one-dimensional DP is from the left or the right, and the number of layers related to the other dimension is the number of layers

You can then get dp[count][flag],flag=1 that indicates how long the count layer will take from the left, and flag=0 indicates how long the count layer will be from the right. And then there's the DFS recursion.

Process

#include <iostream> #include <algorithm> #include <cstring> #include <cstdio>using namespace std;const int M = 2e4 +, MM = 6e4 + 10;int n, x, y, max;int dp[1010][2];struct TnT {int sta, ed, H;} S[1010];bool CMP (TNT A, TNT b) {return a.h > b.h;}    int dfs (int count, int flag) {if (count = = N) {return 0;    } int ans = MM;    if (Dp[count][flag]! =-1) {return dp[count][flag];    } int temp = count;        for (int i = count + 1; I <= n; i++) {temp = i; if (s[count].h-s[i].h <= MAX) {if (flag = = 1) {if (S[count].ed <= s[i].ed && S[co Unt].ed >= S[i].sta) {ans = min (dfs (i, flag) + S[i].ed-s[count].ed, DFS (i, 1-flag) + S[count                    ].ed-s[i].sta);                Break }} if (flag = = 0) {if (S[count].sta <= s[i].ed && s[count].sta >= s[i]. STA) {ans = min (Dfs (i , flag) + S[count].sta-s[i].sta, DFS (i, 1-flag) + S[i].ed-s[count].sta);                Break        }}} else {break; }} if (ans = = MM) {if (temp = = N) {if (S[count].h > MAX) {Dp[count][flag] = ans                ;            return ans;                } else {ans = 0;                Dp[count][flag] = ans;            return ans;        }} Dp[count][flag] = ans;    return ans;        } else {Dp[count][flag] = ans;    return ans;    }}int Main () {int t;    scanf ("%d", &t);        while (t--) {scanf ("%d%d%d%d", &n, &x, &y, &max);        for (int i = 1; I <= n; i++) {scanf ("%d%d%d", &s[i].sta, &s[i].ed, &s[i].h);        } sort (s + 1, s + N + 1, CMP);        S[0].sta = S[0].ed = x, s[0].h = y;        S[n + 1].sta =-M, s[n + 1].ed = m, s[n + 1].h = 0; MEmset (DP,-1, sizeof (DP));        int GG = DFS (0, 0);        GG = min (dfs (0, 1), GG);    printf ("%d\n", GG + y); } return 0;}

Poj 1661 Help Jimmy (memory search)