[破碎的状态] [-4] Hdu 2586
感谢@JCarlson 提供题目和题意
题意:
给你一个带权图,求路径上权值和
做法:
LCA..
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 | #include<set>#include<map>#include<list>#include<queue>#include<stack>#include<string>#include<time.h>#include<math.h>#include<memory>#include<vector>#include<bitset>#include<fstream>#include<stdio.h>#include<utility>#include<sstream>#include<string.h>#include<iostream>#include<stdlib.h>#include<algorithm>using namespace std;int up[40005][25];int sum[40005][25];int father[40005];int up_val[40005];struct edge{ int y; int weight; edge * next;};edge * li[100005];edge * new_edge(){ static edge a[1000005]; static int top=0; return &a[top++];}void inserts(int x,int y,int z){ edge * t=new_edge(); t->y=y; t->weight=z; t->next=li[x]; li[x]=t;}void insert_edge(int x,int y,int z){ inserts(x,y,z); inserts(y,x,z);}int depth[40005];void dfs(int x){ up[x][0]=father[x]; sum[x][0]=up_val[x]; int i; for (i=1;i<20;i++) { if (up[x][i-1]==-1) { up[x][i]=-1; sum[x][i]=sum[x][i-1]; } else { up[x][i]=up[up[x][i-1]][i-1]; sum[x][i]=sum[x][i-1]+sum[up[x][i-1]][i-1]; } } edge * t; for (t=li[x];t!=0;t=t->next) { if (t->y==father[x]) continue; father[t->y]=x; up_val[t->y]=t->weight; depth[t->y]=depth[x]+1; dfs(t->y); }}int lca(int x,int y){ if (depth[x]<depth[y]) swap(x,y); int t=depth[x]-depth[y]; int i; int ans=0; for (i=0;i<20;i++) { if ((1<<i)&t) { ans+=sum[x][i]; x=up[x][i]; } } if (x==y) return ans; for (i=19;i>=0;i--) { if (up[x][i]!=up[y][i]) { ans+=sum[x][i]; ans+=sum[y][i]; x=up[x][i]; y=up[y][i]; } } return ans+sum[x][0]+sum[y][0];}int main(){ #ifdef absi2011 freopen("input.txt","r",stdin); freopen("output.txt","w",stdout); #endif int t; scanf("%d",&t); int zu; for (zu=0;zu<t;zu++) { memset(li,0,sizeof(li)); int n,m; scanf("%d%d",&n,&m); int i; for (i=1;i<n;i++) { int x,y,z; scanf("%d%d%d",&x,&y,&z); x--; y--; insert_edge(x,y,z); } father[0]=-1; up_val[0]=0; depth[0]=0; dfs(0); for (i=0;i<m;i++) { int x,y; scanf("%d%d",&x,&y); x--; y--; printf("%d\n",lca(x,y)); } } return 0;} |
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