input:
4 2 1 2 2 3 4 1 6 2 0 0
output:
Jury #1 Best jury has value 6 for prosecution and value 4 for defence: 2 3
题目大意:
一个人分别对两个派有两个好感度(P,D),让你选m个人,让要m个人的D(j)-P(j)的绝对值(差值和)最小, 若前个条件为相等则选m个人的D(j)+P(j)(和值和)最大的。
分析:
dp。dp[j][k]=选择j个人j个人的差值和为k的最大和值和。k(差值和)是有可能为负数,所以要用偏移量为了保 证全都可行,将偏移量设置成m*20(最大差值为20,那么最大且为负数的最大差值和是-m*20,所以将偏移量设 置成m*20),如此设置后,dp[0][m*20]即为原本的dp[0][0]。
code:
#define frp //#include<bits/stdc++.h> #include<cmath> #include<algorithm> #include<iostream> using namespace std; typedef long long ll; const ll INF = 0x3f3f3f3f; const ll inf = 0x7fffff; const int maxn = 1000; const int MAXN = 1000; int dp[50][MAXN], D[500], P[500]; int path[50][MAXN], ans[MAXN]; int n, m; bool check(int j, int k, int i) { while (j > 0 && path[j][k] != i) { k -= (P[path[j][k]] - D[path[j][k]]); j--; } return j == 0; } void solve() { int cnt = 1; while (cin >> n >> m && (m || n)) { for (int i = 0; i < n; i++) { cin >> P[i + 1] >> D[i + 1]; } memset(dp, -1, sizeof(dp));//默认所有的方案都不可行. memset(path, 0, sizeof(path)); int minInd = m * 20; dp[0][minInd] = 0;//初始状态。 for (int j = 1; j < m + 1; j++) { for (int k = 0; k < minInd * 2; k++) { if (dp[j - 1][k] >= 0) {//当且仅当方案可行的时候可以进行状态转移 for (int i = 1; i < n + 1; ++i) { if (dp[j - 1][k] + P[i] + D[i] > dp[j][k + P[i] - D[i]]) { if (check(j - 1, k, i)) {//看此方之前是否选过i这个人 dp[j][k + P[i] - D[i]] = dp[j - 1][k] + P[i] + D[i]; path[j][k + P[i] - D[i]] = i; } } } } } } int i = minInd, j = 0; while (dp[m][i + j] < 0 && dp[m][i - j] < 0) { j++; } int k = dp[m][i + j] > dp[m][i - j] ? i + j : i - j; cout << "Jury #" << cnt++ << endl; cout << "Best jury has value " << (k - minInd + dp[m][k]) / 2 << " for prosecution and value " << (dp[m][k] - k + minInd) / 2 << " for defence:" << endl; for (int i = 1; i < m + 1; i++) { ans[i] = path[m - i + 1][k]; k -= P[ans[i]] - D[ans[i]]; } sort(ans + 1, ans + 1 + m); for (int i = 1; i < m + 1; i++) { cout << " " << ans[i]; } cout << endl << endl; } } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); #ifdef frp freopen("D:\coding\c_coding\in.txt", "r", stdin); // freopen("D:\coding\c_coding\out.txt", "w", stdout); #endif solve(); return 0; }