delete pics to save space

2.11093.cpp

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+// UVa11093 Just Finish it up
+// Rujia Liu
+#include<cstdio>
+
+const int maxn = 100000 + 5;
+int n, p[maxn], q[maxn];
+
+// returns s if success
+// otherwise, return the station you failed to reach
+// if you failed to reach the start, return -1
+int go(int s) {
+  int fuel = p[s] - q[s];
+  for(int i = (s+1)%n; i != s; i = (i+1)%n) {
+    if(fuel < 0) return i;
+    fuel += p[i] - q[i];
+  }
+  if(fuel < 0) return -1; // this means sum(p) < sum(q), so this case is impossible
+  return s; // success
+}
+
+int solve() {
+  int start = 0;
+  for(;;) {
+    int finish = go(start);
+    if(finish < start) return -1; // wrapped around, or go(start) returns -1
+    if(finish == start) return start;
+    start = finish;
+  }
+}
+
+int main() {
+	
+  int T;
+  scanf("%d", &T);
+  for(int kase = 1; kase <= T; kase++) {
+    scanf("%d", &n);
+    for(int i = 0; i < n; i++) scanf("%d", &p[i]);
+    for(int i = 0; i < n; i++) scanf("%d", &q[i]);
+    int ans = solve();
+    printf("Case %d: ", kase);
+    if(ans < 0) printf("Not possible\n");
+    else printf("Possible from station %d\n", ans+1);
+  }
+  return 0;
+}