mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
114 lines
2.7 KiB
C++
114 lines
2.7 KiB
C++
#include<iostream>
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#include<cstdio>
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#include<cstring>
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#include<algorithm>
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#include<climits>
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using namespace std;
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#define N 505
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#define MAXN 1<<28
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int map[N][N];
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int lx[N], ly[N];
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int slack[N];
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int match[N];
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bool visitx[N], visity[N];
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int n;
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bool Hungary(int u)
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{
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visitx[u] = true;
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for(int i = 1; i <= n; ++i)
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{
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if(visity[i])
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continue;
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else
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{
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if(lx[u] + ly[i] == map[u][i])
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{
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visity[i] = true;
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if(match[i] == -1 || Hungary(match[i]))
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{
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match[i] = u;
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return true;
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}
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}
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else
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slack[i] = min(slack[i], lx[u] + ly[i] - map[u][i]);
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}
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}
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return false;
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}
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void KM_perfect_match()
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{
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int temp;
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for(int i = 1; i <= n; ++i)
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lx[i] = -MAXN;
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memset(ly, 0, sizeof(ly));
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for(int i = 1; i <= n; ++i)
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for(int j = 1; j <= n; ++j)
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lx[i] = max(lx[i], map[i][j]);
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for(int i = 1; i <= n; ++i)
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{
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for(int j = 1; j <= n; ++j)
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slack[j] = MAXN;
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while(1)
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{
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memset(visitx, false, sizeof(visitx));
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memset(visity, false, sizeof(visity));
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if(Hungary(i))
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break;
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else
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{
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temp = MAXN;
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for(int j = 1; j <= n; ++j)
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if(!visity[j])
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temp = min(temp, slack[j]);
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for(int j = 1; j <= n; ++j)
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{
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if(visitx[j])
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lx[j] -= temp;
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if(visity[j])
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ly[j] += temp;
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else
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slack[j] -= temp;
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}
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}
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}
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}
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}
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int main()
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{
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int m;
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int a, b, cost;
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int ans;
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bool flag;
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while(scanf("%d%d", &n, &m) != EOF)
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{
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ans = 0;
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flag = true;
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memset(match, -1, sizeof(match));
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for(int i = 1; i <= n; ++i)
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for(int j = 1; j <= n; ++j)
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map[i][j] = -MAXN;
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for(int i = 1; i <= m; ++i)
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{
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scanf("%d%d%d", &a, &b, &cost);
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if(-cost > map[a][b])
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map[a][b] = -cost;
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}
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KM_perfect_match();
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for(int i = 1; i <= n; ++i)
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{
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if(match[i] == -1 || map[ match[i] ][i] == -MAXN)
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{
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flag = false;
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break;
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}
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ans += map[match[i]][i];
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}
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if(flag)
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printf("%d\n", -ans);
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else
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printf("-1\n");
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}
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return 0;
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}
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