modify code

Author: algorithmzuo

src/class165/Code03_Envy1.java

@@ -25,7 +25,7 @@ public class Code03_Envy1 {
 	// 节点u、节点v、边权w
 	public static int[][] edge = new int[MAXN][3];
 	// 节点u、节点v、边权w、问题编号i
-	public static int[][] queryEdge = new int[MAXN][4];
+	public static int[][] queries = new int[MAXN][4];
 
 	// 可撤销并查集
 	public static int[] father = new int[MAXN];
@@ -70,28 +70,33 @@ public static void prepare() {
 			siz[i] = 1;
 		}
 		Arrays.sort(edge, 1, m + 1, (a, b) -> a[2] - b[2]);
-		Arrays.sort(queryEdge, 1, k + 1, (a, b) -> a[2] != b[2] ? (a[2] - b[2]) : (a[3] - b[3]));
+		Arrays.sort(queries, 1, k + 1, (a, b) -> a[2] != b[2] ? (a[2] - b[2]) : (a[3] - b[3]));
 		Arrays.fill(ans, 1, q + 1, true);
 	}
 
 	public static void compute() {
-		int ei = 1;
+		int ei = 1, queryId, unionCnt;
 		for (int l = 1, r = 1; l <= k; l = ++r) {
-			for (; ei <= m && edge[ei][2] < queryEdge[l][2]; ei++) {
+			while (r + 1 <= k && queries[l][2] == queries[r + 1][2] && queries[l][3] == queries[r + 1][3]) {
+				r++;
+			}
+			// 添加小于当前边权的边，利用Kruskal算法增加连通性，ei是不回退的
+			for (; ei <= m && edge[ei][2] < queries[l][2]; ei++) {
 				if (find(edge[ei][0]) != find(edge[ei][1])) {
 					union(edge[ei][0], edge[ei][1]);
 				}
 			}
-			while (r + 1 <= k && queryEdge[l][2] == queryEdge[r + 1][2] && queryEdge[l][3] == queryEdge[r + 1][3]) {
-				r++;
+			queryId = queries[l][3];
+			if (!ans[queryId]) {
+				continue;
 			}
-			int unionCnt = 0;
+			unionCnt = 0;
 			for (int i = l; i <= r; i++) {
-				if (find(queryEdge[i][0]) == find(queryEdge[i][1])) {
-					ans[queryEdge[i][3]] = false;
+				if (find(queries[i][0]) == find(queries[i][1])) {
+					ans[queryId] = false;
 					break;
 				} else {
-					union(queryEdge[i][0], queryEdge[i][1]);
+					union(queries[i][0], queries[i][1]);
 					unionCnt++;
 				}
 			}
@@ -126,10 +131,10 @@ public static void main(String[] args) throws IOException {
 			for (int j = 1, ei; j <= s; j++) {
 				in.nextToken();
 				ei = (int) in.nval;
-				queryEdge[++k][0] = edge[ei][0];
-				queryEdge[k][1] = edge[ei][1];
-				queryEdge[k][2] = edge[ei][2];
-				queryEdge[k][3] = i;
+				queries[++k][0] = edge[ei][0];
+				queries[k][1] = edge[ei][1];
+				queries[k][2] = edge[ei][2];
+				queries[k][3] = i;
 			}
 		}
 		prepare();

src/class165/Code03_Envy2.java

@@ -22,11 +22,11 @@
 //    return x.w < y.w;
 //}
 //
-//struct QueryEdge {
+//struct Query {
 //    int u, v, w, i;
 //};
 //
-//bool QueryEdgeCmp(QueryEdge x, QueryEdge y) {
+//bool QueryCmp(Query x, Query y) {
 //    if(x.w != y.w) {
 //        return x.w < y.w;
 //    } else {
@@ -38,7 +38,7 @@
 //int n, m, q, k;
 //
 //Edge edge[MAXN];
-//QueryEdge queryEdge[MAXN];
+//Query queries[MAXN];
 //
 //int father[MAXN];
 //int siz[MAXN];
@@ -81,30 +81,34 @@
 //        siz[i] = 1;
 //    }
 //    sort(edge + 1, edge + m + 1, EdgeCmp);
-//    sort(queryEdge + 1, queryEdge + k + 1, QueryEdgeCmp);
+//    sort(queries + 1, queries + k + 1, QueryCmp);
 //    for (int i = 1; i <= q; i++) {
 //        ans[i] = true;
 //    }
 //}
 //
 //void compute() {
-//    int ei = 1;
+//    int ei = 1, queryId, unionCnt;
 //    for (int l = 1, r = 1; l <= k; l = ++r) {
-//        for (; ei <= m && edge[ei].w < queryEdge[l].w; ei++) {
+//        while (r + 1 <= k && queries[l].w == queries[r + 1].w && queries[l].i == queries[r + 1].i) {
+//            r++;
+//        }
+//        for (; ei <= m && edge[ei].w < queries[l].w; ei++) {
 //            if (find(edge[ei].u) != find(edge[ei].v)) {
 //                Union(edge[ei].u, edge[ei].v);
 //            }
 //        }
-//        while (r + 1 <= k && queryEdge[l].w == queryEdge[r + 1].w && queryEdge[l].i == queryEdge[r + 1].i) {
-//            r++;
+//        queryId = queries[l].i;
+//        if (!ans[queryId]) {
+//            continue;
 //        }
-//        int unionCnt = 0;
+//        unionCnt = 0;
 //        for (int i = l; i <= r; i++) {
-//            if (find(queryEdge[i].u) == find(queryEdge[i].v)) {
-//                ans[queryEdge[i].i] = false;
+//            if (find(queries[i].u) == find(queries[i].v)) {
+//                ans[queryId] = false;
 //                break;
 //            } else {
-//                Union(queryEdge[i].u, queryEdge[i].v);
+//                Union(queries[i].u, queries[i].v);
 //                unionCnt++;
 //            }
 //        }
@@ -127,10 +131,10 @@
 //        cin >> s;
 //        for (int j = 1, ei; j <= s; j++) {
 //            cin >> ei;
-//            queryEdge[++k].u = edge[ei].u;
-//            queryEdge[k].v = edge[ei].v;
-//            queryEdge[k].w = edge[ei].w;
-//            queryEdge[k].i = i;
+//            queries[++k].u = edge[ei].u;
+//            queries[k].v = edge[ei].v;
+//            queries[k].w = edge[ei].w;
+//            queries[k].i = i;
 //        }
 //    }
 //    prepare();