HDU 6326 Problem H. Monster Hunter （贪心+并查集）*

 

Problem H. Monster Hunter Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 524288/524288 K (Java/Others) Total Submission(s): 773    Accepted Submission(s): 194   Problem Description Little Q is fighting against scary monsters in the game ``Monster Hunter''. The battlefield consists of n intersections, labeled by 1,2,...,n , connected by n−1 bidirectional roads. Little Q is now at the 1 -th intersection, with X units of health point(HP). There is a monster at each intersection except 1 . When Little Q moves to the k -th intersection, he must battle with the monster at the k -th intersection. During the battle, he will lose ai units of HP. And when he finally beats the monster, he will be awarded bi units of HP. Note that when HP becomes negative(<0 ), the game will over, so never let this happen. There is no need to have a battle at the same intersection twice because monsters do not have extra life. When all monsters are cleared, Little Q will win the game. Please write a program to compute the minimum initial HP that can lead to victory.     Input The first line of the input contains an integer T(1≤T≤2000) , denoting the number of test cases. In each test case, there is one integer n(2≤n≤100000) in the first line, denoting the number of intersections. For the next n−1 lines, each line contains two integers ai,bi(0≤ai,bi≤109) , describing monsters at the 2,3,...,n -th intersection. For the next n−1 lines, each line contains two integers u and v , denoting a bidirectional road between the u -th intersection and the v -th intersection. It is guaranteed that ∑n≤106 .       Output For each test case, print a single line containing an integer, denoting the minimum initial HP.     Sample Input   1 4 2 6 5 4 6 2 1 2 2 3 3 4     Sample Output   3     Source 2018 Multi-University Training Contest 3     Recommend chendu   |   We have carefully selected several similar problems for you:  6361 6360 6359 6358 6357

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